Episode 40: Learn how to manage your time more efficiently by developing a study SYSTEM that will allow you to really relax when you’re away from the books.

 Study Techniques for the New MCAT [42:10] Play Now | Play in Popup | Download (2448)

This episode is the first in a multi-part series of Frequently Asked Questions. Based on a recent survey, Dr. Dan groups students’ answers by theme.

Discover very high yield tips for managing your time, mastering the Clinical Years, getting a better MCAT score and more. If you listen to the podcast, you’ll have a better understanding of the appropriate use of memorization techniques and why so many students spend most of their time studying the wrong way for the MCAT. Enjoy!

Students Owning Cars: Is it Really Necessary?

We all know that they are too many cars on the roads, and the numbers of drivers and subsequent cars just keeps on growing. One problem this causes in increased traffic congestion and another more serious problem is the terrible affect more cars have on the environment. People who own cars will provide plenty of valid reasons for needing one, and many simply can’t do without them. On the other hand, there are alternatives and schemes in place that make it easier for students to do without a car. Also, students are at a point in their lives where they have to borrow money and budget carefully to be able to afford their education. An extra expense like buying and running their own car is something that most could certainly do without.

The Expense of Having Your Own Car

Owning, running, and maintaining a car isn’t cheap. There are lots of costs involved, which can become a real hindrance to students who have to live on a limited income. The fact that the majority of students are fairly new to driving, a lot for thought has to go into what is the best car for students. Safety is paramount, but also the initial cost of the car, along with how economical it is to run, has to be considered too. Most students will not have the cash required to buy a car outright, so different types of car credit has to be weighed up as well, to make sure you get the best deal and aren’t lumbered with high interest payments. Even when you have your car, the costs don’t stop there. You’ll have to arrange some good, comprehensive, student discount auto insurance if you want to save yourself some cash, because there are fuel and maintenance costs to pay for while you use the car.

All in all, having your own car will be a constant cost for you, so if there is any way you can get by without one, try to avoid it. Student’s already have to borrow large sums of money just to fund their studies, so having another expense to factor in can only make matters worse.

Alternatives to Owning a Car

Luckily for students, there are a variety of alternatives to actually owning their own car. Students can benefit from discounts on public transport, which can add up to significant saving when totalled up over a year. Riding a bicycle is a fantastic way to get around cheaply, and you will be doing your bit for the environment by not travelling in a pollution emitting motor vehicle. Again, you may well be able to find bike retailers who offer discounts to students, so that you can get money off an already affordable bicycle.

A new service that has been recently developed is called ‘Wheelz,’ which is an innovative car sharing service designed specifically for students. The idea is that the people who already own cars when they begin college or university can list their vehicle as available for car sharing. The incentive for the car owner is a financial reward for driving their fellow students to their desired destination, and for the students that need a car they get a cheap ride to their destination without the expense of owning a car. Students can also arrange to rent their car to other students, and all this can be arranged through an Android, iPad, and iPhone app.

It’s a fairly new service that currently only operates in California, at UCLA, USC, UC Berkeley, and Stanford, but the new company hopes to expand rapidly. They have a form at their website, wheelz.com, where students can request that the service is started at their educational institution.

Reasons Why Students Need Cars

There will always be students who really need their own cars, especially those that move away from the campus during their later years of study. There is also the issue of needing transport to get to an internship in the city, and interviews for possible jobs when you graduate. Medical students can be under even more pressure, especially if they are working late nights or early morning at hospitals when public transport is scarce.

The disadvantages and advantages of owning a car have to be weighed up by each individual student, but each should start the process with the view point that owning a car is not necessarily a good thing. While it gives you increased freedom and some extra opportunities, it is a cost that every student can do without.

Episode 39: Short of getting a literature degree, find out Dr. Dan’s expanded resource and study tips that can help you overcome the MCAT if you have been plagued by repeated, unsatisfactory scores.

 Top 7 MCAT Tips - When All Other Methods Have Failed [41:21] Play Now | Play in Popup | Download (5029)

MCAT Statistics

Two-thirds of entering medical students have a science undergraduate background and often struggle with the MCAT Verbal Reasoning section. Despite repeated attempts to increase a sub-par MCAT score, a substantial percentage of students that take the MCAT again and again are unable to increase their MCAT score impressively.

Having doubts about the MCAT?

I know I did. After 2 months and $2,000 paying for a “professional” MCAT Prep Course, my MCAT score did not go up. Are you in that situation too? If not, try to avoid it – take it from me!

The MCAT is the most unusual test you’ll ever take. It goes into painstaking detail about topics that you’ve never heard about, unlike ‘most’ final exams. J

If this sounds like you, then pay attention.

Top 7 MCAT Tips – When All Other Efforts Have Failed

Do these in order, like a checklist:

1. Watch this video on how to Master the MCAT.
2. Study the Silver Bullet MCAT book by Dr. Brett Ferdinand.
3. Take real AAMC – released, old MCAT tests only.
4. As you study, determine the patterns of mistakes that you are making on the old MCAT tests. (use #1 and #2 above to help you figure this out)
5. Immerse yourself in the “language” of Verbal Reasoning if that section is troubling you. Read passages DAILY until you take the MCAT from Atlantic Monthly, New York Times, and similarly cerebral sources. Then, do the following with each passage: AA Determine what the author’s opinion is about the topic. B) Determine what an opposing view might be. C) Become a critic of every passage you read, whether you agree or not, and construct arguments that would go against the author’s opinion.
6. Begin thinking of your MCAT troubles in a positive way using the Success Story Format.
7. Attend regular, live Medical Mastermind Community Teleconferences and use the private, members-only My Blog to track your progress and continue learning.

Here’s the link to the Google Calendar that can be “added to your Google Calendar” at the bottom for automatic reminders of the upcoming Medical Mastermind Community Teleconference Series.

Episode 38: In this episode, you’ll learn the statistics of the first-ever peer-reviewed data on a revolutionary approach to an age-old problem – increasing MCAT and GPA scores!

 Standard Podcast [41:10] Play Now | Play in Popup | Download (4601)

How to Increase Your MCAT Score

1. Use a Mastermind approach. Instead of trying to figure out what works through trial and error, why not rely on people with experience to help give you ideas for how to KNOW you’ll reach your goals.
2. Study how you study. In the Medical Mastermind Community, you’ll learn how to design a custom system for yourself so that you’ll know how well you’re doing weeks before your actual exam.
3. Watch this video on how to Master The MCAT.

Beginning A Medical Career

Who knew that 5 years ago when I started podcasting that it would turn into the first peer-reviewed PreMed prep course! Notice that you wouldn’t balk at spending $1000-$2000 on a professional MCAT course such as Kaplan but they don’t even publish data on if it works.

In the past year, I’ve written and published a record-breaking amount of scientific literature as an intern:

• 4 papers: one case report accepted for publication, one systematic review on treatments for burnout in medical students, and 2 for increasing GPA, MCAT scores and acceptance into medical school
• 3 poster presentations: one already presented (discussed in this podcast episode; click audio link above), one pending acceptance at the Science of Eliminating Health Disparities conference, and one I that was accepted but that I had to turn down because I was too busy!
• 3 research projects: two completed and the third is pending approval from the institutional review board

Five more papers/projects are in the hopper! Astounding, eh? No, it’s the Mastermind concept at work, and it can work for YOU TOO!

How to increase your GPA

There is no escaping it – you HAVE TO watch all 9 videos of our Study Techniques Course. Once you pay and login to this website, click on EXAM PREP in the upper-right hand corner. The Study Techniques Course is found on the first 3 tabs of that pull-down menu.

It will change your life or your money back.

Read the Medical Mastermind Community Review

Dear Doctor Dan,

About a year and a half ago, I joined your Medical Mastermind Community. I wrote to you unsure as to whether I should attend the Caribbean medical schools I had been accepted to and start then, or study for the MCAT and apply to US medical schools. I opted to attend the Carib school, and here I am 14 out of 16 months later, 60 days away from completing the last courses of Basic Sciences. I am currently taking Pathology II, Pharmacology, Medical Ethics and Behavioral Science.

The study techniques I have learned by being a member have been fantastic. I record every lecture, I listen to them evenings and weekends sped up on faster play speeds, and repeatedly approaching block exam time. This has proven to be a great technique for me, because I can listen harder during the in-person lecture, instead of trying to listen AND write  voraciously. I save most of the writing until that evening with my printed power point notes and text book. I never imagined how much information one can miss the first time you hear a lecture in class. I end up adding so much more on the power point printed copy, in addition to text book notes. Hearing the instructor tell “the whole story” again and again made a huge difference in my performance, even on “hyper-speed.”

Additionally, I do make a checklist of “testable items” for each topic. I actually print out the table of contents from my PDF versions of my text book, highlight the lecture topics, the date it was taught, and check off each concept every time I go through it (4-5 times).

Next semester, we (and most Carib med schools) have a mandatory 5th semester review for the USMLE, which takes place back in the U.S. I will be in touch with you prior to then, for direction from your  “community.”

Sincerely,
Lisa Lamar – Successful 4th Semester Student

Episode 37: This is the second in our Master the MCAT Core Sciences content from studentdoctorpodcast.com. The first edition on DNA was a success and I’m happy to be publishing number 2 of 50 MCAT MP3′s here on the Premed Podcast.

 MCAT Biology 2/50: Digestion, bone, and muscularity [26:47] Play Now | Play in Popup | Download (6716)

At the time of this podcast release (March 3, 2012), I’m offering a free 30 days’ access to the Master The MCAT program, and all of the Study Techniques and Dr. Dan’s personal MCAT notes for positive reviews in iTunes, YouTube, and Facebook. You can get 10 days’ access for a positive review in each place, for a total of 30.

Even if you’re just now finding this podcast months or years from the release date, you should still write the positive review! You’d be surprised how often only grumpy people fill out reviews so it will take a lot more positive ones than I ever thought to balance that out.

Once you write your positive reviews in Facebook, iTunes, and YouTube, click on the Contact page above and shoot me a personal email.

I look forward to your participation in the Medical Mastermind Community from that point forward!

Best,

Dr. Dan

Episode 35: Did you know there will be sociology, psychology and an increased emphasis on critical thinking and reasoning skills on the new MCAT? Well, some of the changes are already in effect and have been for a few years!

 Master The MCAT 2015 New Changes [23:23] Play Now | Play in Popup | Download (3279)

In this episode, Dr. Dan explains the why, what and when of the new 2015 MCAT changes that are coming.

Why change the new 2015 MCAT?

The AAMC cites that increasing population diversity and new medical science have spurred their changes. Read their full recommendations here:

The New 2015 MCAT Changes

What will the MCAT changes be?

A new psychological, sociological and biological foundations of behavior sections will be included, according the above report.

Also, an increased emphasis on Critical Analysis and Reasoning Skills will be placed. Of course, these have been tested for many years in various ways. Interestingly, in 2009, the AAMC released a book that revealed the 4 cognitive skills being used to test every MCAT passage.

The 4 cognitive skills ALWAYS being tested in any MCAT passage are:

1. Evaluation
2. Application
3. Comprehension
4. Incorporation

Strikingly, only 25% of these questions types (1/4) require any previous knowledge to answer the question; no wonder the literature majors do so well on Verbal Reasoning!

Can you name the three cognitive skills that require NO OUTSIDE INFORMATION?

If not, you’re apparently like most students who take the MCAT. No MCAT prep company really uses these cognitive skills, published by the AAMC itself – who writes the MCAT, to teach people about the MCAT.

It’s time you learn about the Master The MCAT program, brought to you exclusively from the Medical Mastermind Community. Check it out…

Episode 34: Learn new tips on MCAT prep classes, study techniques, the mindmap CD, personal essays for DO applications, and a recommended flashcard tool.

 Premed Questions about the MCAT [45:55] Play Now | Play in Popup | Download (2558)

In this episode, Dr. Dan breaks his usual format in order to answer listener questions.

Premed Questions and Answers

You have to listen to the podacst to get the answers, but here are the questions that he addresses:

1. Do you have any new tips and tricks regarding MCAT prep classes?
2. I got a 24 on the AAMC MCAT test #3 and have one month to study for the MCAT. Shall I go for it?
3. I received an F in Physics in undergrad, but then got an A later in grad school. Do you think it will seriously affect my chances of getting into medical school?
4. If I upgrade my subscription in the Medical Mastermind Community, what CD’s will I receive? Where is the CD shipping schedule?
5. I’m overwhelmed by the amount of material inside the Mastermind Community and on the Mindmap CD. Do I have to read it all?
6. Thank you for giving me feedback on my personal statement. Should I comment on the philosophy of osteopathic medicine in my DO application?

Here is the Flashcard Program that was mentioned on the show: ANKI srs

Episode 33: Listen to this science content review and learn its format for your own audio notes.

 Standard Podcast [15:47] Play Now | Play in Popup | Download (3527)

Hematopoietic Agents

Notice how these show notes are arranged: a list review of hematopoietic agents (that cause red blood cell production), core text review, and an audio version.

This fits into the Mastermind Study System after you have attended lecture, read the material once, and are reviewing your notes and organizing them for the first time:

MCAT Study Notes:

1.      Growth Factors

2.      Erythropoietin

3.      GCSF – granulocyte colony stimulating  factor

Read the rest of this »

Episode 32: A different dentist weighs in this month, but wait – he’s applying to medical school! What? You’ve never heard a podcast like this before…

 Pre-Dental Podcast [21:17] Play Now | Play in Popup | Download (1146)

A Dentist Turned Pre-Med

Seriously?

You judge for yourself, but I think that the same decision factors that the last dentist we interviewed used to decide TO CHOOSE dentistry as a career, this dentist looks at them totally differently and CHOOSES NOT to stay in dentistry.

Episode 31: The content dentist. Next month will be a discontented dentist turned pre-med! Learn why they made their choice and how to make your own.

 Pre-Dentistry Podcast [16:33] Play Now | Play in Popup | Download (1152)

Pre-Dentistry

I’ve had numerous questions about other health fields besides pre-medicine. So, in this 2-part podcast series we will hear from two dentists:

Five Reasons To Become A Dentist

Listen to the podcast and discover the top reasons why Dr. John made his career choice to become a dentist.

What I’ve always found fascinating is that these same decision factors can be used to justify the opposite – listen to next month’s podcast to see exactly how that can happen…

Episode 30: Doctor Dan explains the average MCAT for allopathic matriculates in the United States.

 Average MCAT [12:17] Play Now | Play in Popup | Download (2571)

The Average MCAT

In 2010, the Association of American Medical Colleges (no affiliation) reported the following numbers from the entering class of allopathic medical students:

Mean Total MCAT Score = 31.1, with a standard deviation of 4.1

Read the rest of this »

MCAT Score Release

Your heart is pounding.

Thoughts are racing through your head about how you life will change if you get accepted into medical school.

You check your email and there it is, your MCAT score – in black and white.

Your MCAT Score

If it is over 30, you should be happy. If not, you have cause for concern.

Either way, most people worry about their score being too low – even if it is way above average?

Why?

Because the MCAT Score isn’t your goal! Getting into medical school isn’t even your goal.

My students know well that it is a fulfilling career in medicine that is the goal and all of the hurdles are only that – hurdles.

Good MCAT SCORES

Just like the rest of us, you don’t usually let yourself relax and celebrate a good MCAT score. You immediately launch into a vigorous course of action towards your next step – applying to medical school.

Episode 29: Harvard advice on the medical school personal statement. 6 Don’ts & 6 Do’s

 Medical School Personal Essay Help [20:39] Play Now | Play in Popup | Download (2382)

Personal Essay Help

www.InsiderMedicalAdmissions.com

6 Don’ts of Writing Personal Essays:

1. Don’t be generic.
2. Don’t use personal medical experiences.
3. Don’t be vague.
4. Don’t write more than one page.
5. Don’t use flowery language.
6. Don’t use quotations.

6 Do’s of Writing Personal Essays:

1. Do start early, say during the winter before your application cycle.
2. Do make an outline.
3. Do show, don’t tell.
4. Do start with a zinger and end with a clencher.
5. Do be proud.
6. Do address severe deficiencies in the essay. (learn how to do this yourself here)

Episode 28: This is where I ask him the big question – you don’t want to miss his answer and the reason he gives for it!

 Do Caribbean medical schools suck? part 2 Play Now | Play in Popup | Download (1574)

Caribbean Medical Schools

This is the final reveal!

Take a listen and see exactly why people complain about the quality of medical students coming from “some” Caribbean medical schools.

In summary, this two-part series on “Do Caribbean Medical Schools Suck” has addressed the following points:

• The quality of medical training is on par with US Medical Schools
• The standard of care is often not based on American culture
• The content for licensing in the US is often outdated

What do YOU think? Do they suck?

The opinions expressed in this interview are solely those of the interviewee and do not necessarily reflect those of Premedical Solutions, LLC or The Medical Mastermind Community and its members.

Episode 27: You have NEVER heard this stuff before – I promise or your money back…

 Do Caribbean Medical Schools Suck? [52:29] Play Now | Play in Popup | Download (1898)

The opinions expressed in this interview are solely those of the interviewee and do not reflect the opinions of Premedical Solutions, LLC. yada yada yada

Episode 26: Learn the “Master Key” to taking notes and converting them for the Free Recall Study Method. Dr. Dan discovered it independently and, years later, found that he was not alone.

 How To Study For The MCAT [20:11] Play Now | Play in Popup | Download (3049)

In this episode, I’m going to tell you exactly how to prepare your notes from class and employ the free recall method. Something like one or two weeks before your exams to give you a serious boost to your exams scores. Now this is no BS, this is no hype. I’m just excited about it. Apollo audio books actually uses this exact same format which I discovered on my own as a pre med in all of their professional medical school audio courses. And right now, I’m in negotiations with Princeton review for you guys, to get them to create a full blown MCAT version.

Read the rest of this »

Episode 25: Doctor Dan does an expose on how his Physics knowledge has stayed strong for so long! Listen to the podcast to learn who she is…

 MCAT Physics [15:03] Play Now | Play in Popup | Download (8308)

MCAT Physics

Vectors

Scalar quantities, such as temperature, have magnitude only and are specified by a number with a unit, 67 degrees Celsius and obey the rules of ordinary algebra.  Vectors, such as displacement, have both magnitude and direction, six meters west and obey the special rules of vector algebra.

X and Y Coordinates

Two vectors A and B may be added geometrically by drawing them to a common scale and placing them head to tail.  The vector connecting the tail of A to the head of B is the sum vector.  To subtract B from A, reverse the direction of B and then add to A.  The component A_X and A_Y of any vector A are the perpendicular projections of A on the coordinate axes.

Pythagoras’ theorem

Analytically, the components are given by A_X=A (cos theta) and A_Y=A (sine theta).  Given the component, we can reconstruct the vector from:  A is given by the square root of the quantity, A_X² + A_Y², which is a derivation of the Pythagoras’ theorem.

Kinematics

The motion of a body is described by giving its position or displacement, its velocity and its acceleration.  The average speed is defined as the distance traveled divided by the elapsed time.  The average velocity is the displacement vector divided by the elapsed time.

Displacement

Displacement is the vector representing the position of an object relative to its position at some chosen earlier time, or its point of origin.  Whereas speed is a scalar quantity, velocity is a vector.  The instantaneous velocity whose magnitude is the same as the instantaneous speed is the average velocity taken over an indefinitely short period of time.

Acceleration

Velocity as well other qualities describing motion are always measured with respect to some frame of reference.  Acceleration is the rate of change of velocity.  The change of velocity divided by the elapsed time, it is a vector.  If an object moves in a straight line with constant acceleration, the velocity, V, and the acceleration, A, are related to the initial velocity V₀ and the displacement, D, and the time, T, by the equations-V=V₀ + AT; D, the displacement, equals V₀T + ½AT²; V²=V₀² + 2AD.  The mean velocity equals V + V₀/2.  Objects allow to fall freely without air resistance all fall with the same constant acceleration, G=9.8 meters/second².

Motion and force.

Newton’s 3 Laws

Number 1

Newton’s three laws of motion are the basic laws explaining motion.  Newton’s first law states that if the net force on an object is zero, the object at rest remains at rest and an object in motion remains in motion in a straight line with constant velocity.  The tendency of a body to resist a change in motion is called inertia.  Mass is a measure of inertia.  Weight refers to the force of gravity on an object.

Number 2

Newton’s second law states that the acceleration of a body is directly proportional to the net force acting on it and inversely proportional to its mass.  F=ma, where F is the force, m is the mass, and A, the acceleration.  Force, which is a vector, is a push or a pull.  More precisely, Newton’s second law can be used as a definition of force as that action which is capable of accelerating an object.  Net force refers to the vector sum of all forces acting on a body. The force of gravity acting on a body is the product of its mass times the acceleration of gravity.

Number 3

Newton’s third law states that when every one body exerts a force on a second body, the second exerts an equal force on the first in the opposite direction.  A consistent set of units must always be used when making calculations.  SI unit s are the standard ones used for scientific work and these include the meter, kilogram and second.

Friction

When two bodies are in contact or slide over one another, the force of friction each exerts on the other can be written force of friction equals mu N, where N is the normal force, the force each body exerts on the other perpendicular to the surface in contact.  Mu is the coefficient of kinetic friction if the bodies are moving relative to each other.  If they are not moving, the above equation gives the maximum friction force where mu is the coefficient of static friction.

Projectile motion

That of an object moving through the air can be analyzed as two separate motions in the horizontal and vertical directions.  If air resistance can be ignored, the horizontal motion is at constant velocity where the vertical motion is uniformly accelerated and is the same as for the body falling vertically under the action of gravity.

Circular motion and gravitation

Angular quantities are defined in analogy with linear quantities.  Angles can be measured in degrees, revolutions or radians, where two pi radians is equal to one revolution, which is equal to 360 degrees.  A particle moving with constant speed, V, in a circle of radius, R, has a linear centripetal, which means towards the center acceleration.  That acceleration is given by V²/R.  Because the velocity vector is continually changing in direction, that’s why there is an acceleration.  A force acting towards the center is thus needed to keep a particle revolving in a circle.  If the particle is revolving in a circle with non-uniform speed, it will have both centripetal and tangential linear acceleration.

Gravity

Newton’s law of universal gravitation states that every body in the universe attracts every other body with a force proportional to the product of their two masses and inversely proportional to the square of the distance between them.  It is this force of gravity that keeps the moon in its orbit around the Earth and the planets in their orbits around the sun.  The dynamics of rotation is analogous to the dynamic of linear motion.  Force can be replaced by torque which is defined as the product of force times the perpendicular distance from the pivot point.

Inertia

Mass is replaced by the moment of inertia which depends not only on the mass of the body, but also on how the mass is distributed about the axis of rotation.

Angular Acceleration

And linear acceleration is replaced by angular acceleration.  So, instead of seeing F=ma as we previously saw, now we have the rotational equivalent of Newton’s second law, which is tau, the torque force, equals I, the moment inertia times alpha, the angular acceleration.

Center of Gravity

The center of gravity of a body is that point at which the force of gravity can be considered to act for purposes of determining the motion of the body as a whole.  The complete motion of a body can be described as the translational motion of its center of gravity, plus the rotation about its center of gravity.

Equilibrium

We will now discuss bodies in equilibrium.  A body at rest or one in uniform motion at constant velocity is said to be in equilibrium.  The determination of the forces within a structure at rest is the field called statics.  The two necessary conditions for a body to be in equilibrium are:  one, the vector sum of all the forces on it must be zero and, two, the sum of all the torques calculated about any arbitrary point as axis must also be zero.  It’s important when doing statics problems to apply the equilibrium conditions to only one body at a time.

A body in static equilibrium is said to be in stable, unstable or neutral equilibrium, depending on whether a slight displacement leads to a return to the original position, that would be stable equilibrium, or further movement, which would be unstable, or a rest in the new position, which would be neutral equilibrium.  An object in stable equilibrium is also said to be in balance.

Elasticity

Hooke’s law applies to many elastic solids, and states that the change in length of an object is proportional to the applied force.  If the force is too great, the object will exceed its elastic limit, which means it will no longer return to its original shape when the distorting force is removed.  If the force is even greater, the ultimate strength of the material can be exceeded and the object fractures.

Stress

The force per unit area acting on a body is called the stress.  And the resulting fractional change in length is called the strain.  The stress on a body is present within the body and can be of three types-compression, tension and shear.  The ratio of stress to strain is called the elastic modulus of the material.  Young modulus applies for compression and tension and the shear modulus for shear.

Both moduli apply to an object whose volume changes as a result of pressure on all sides.  All three moduli are constants for a given material when distorted within its elastic region.

The subject of statics is especially useful for calculating forces within muscles and bones and in structures such as buildings and bridges.

Momentum and energy

The momentum, P, of a body is defined as its mass times its velocity where P=MV.  In terms of momentum, Newton’s second law can be written, F, the force equals dP over dT, which is the rate of change of a momentum equals the net applied force.

Momentum is a conserved quantity.  The law of conservation of a momentum states that the total momentum of an isolated system of objects remains constant.  An isolated system is one on which the net external force is zero.

Work

Work is done on an object by a force when the force moves the object through a distance, D.  If the direction of the force makes an angle, theta, with the direction of motion, the work done by this force is given by W=FD (cos theta).

Energy

Energy is defined as the ability to do work.  Both work and energy are measured in Joules, where one Joule equals one Newton meter.  Kinetic energy is energy of motion.  A body of mass, m, and speed, V, has translational kinetic energy equal to ½ MV².

An object can have potential energy by virtue of its position or shape.  Examples are gravitational potential energy, which is equal to mgh, where h is the height of the object of mass, m, above an arbitrary reference point.  An object can also have elastic potential energy, such as a compressed spring.  An object can also have chemical, electrical, or nuclear energy.

The change of potential energy of an object when it changes position is defined as the work needed to take it from one position to the other.  The work energy theorem states that the net work done on a body by the net force equals the change in kinetic energy of that body.

The law of conservation of energy states that energy can be transformed from one type to another, but the total energy remains constant.  It is valid even when friction is present since the heat generated by friction can be considered a form of energy.  Momentum is conserved in any collision between objects.  Energy is conserved, too, but kinetic energy only in so-called elastic collisions in which other forms of energy do not change.

Power

Power is defined as the rate at which work is done or the rate in which energy is transformed.  The SI unit of power is the watt, where 1 watt equals one Joule per second.

Fluids

Now, let us look at fluids.  The three common phases of matter are solid, liquid and gas.  Liquids and gases are collectively called fluids.  Meaning they have the ability to flow.  The density of a material is defined as its mass per unit volume.  Specific gravity is the ratio of the density of the material to the density of water.  Pressure is defined as force per unit area.  The pressure at a depth, h, in a liquid is given by rho gh, where rho is the density of the liquid and g is the acceleration due to gravity.

In addition, if an external pressure is applied to a confined fluid, this pressure is transmitted throughout the fluid.  This is known as Pascal’s principle.  Pressure is measured using manometer or other types of gauge.  A barometer is used to measure atmospheric pressure.  Standard atmospheric pressure, which is the average at sea level, is 1.01 x 10⁵ Newton per meter squared.

Archimedes Principle

Archimedes principle states that an object submerged wholly or partially in a fluid is bouoyed up by a force equal to the weight of fluid it displaces.  This principle is used in a method to determine specific gravity and explains why objects whose density is less than that of liquid will float in that liquid.

Fluid flow rate is the mass or volume of fluid that passes a given point per unit time.  The equation of continuity states that for an incompressible fluid flowing in an enclosed tube, the product of the velocity of flow and the cross-sectional area of the tube remains constant.  AV is a constant.

Bernoulli’s Equation

Bernoulli’s equation tells us that where the velocity of a fluid is high, the pressure in it is low.  And where the velocity is low, the pressure is high.  Bernoulli’s principle explains many common phenomena.  Fluid flow can be characterized either as streamline, sometimes called laminar in which the layers of fluid move smoothly and regularly along paths called streamlines, or it can be characterized as turbulent in which case the flow is not smooth and regular, but it’s characterized by irregularly shaped whirlpools.

Viscocity

Viscosity refers to friction within a fluid that prevents the fluid from flowing freely and is essentially a frictional force between different layers of fluid as they move pass one another.

Temperature and the kinetic theory.  The atomic theory of matter postulates that all matter is made up of tiny entities called atoms.  Some substances are made up of only one type atom, and these are called elements.  Atoms can combine to form molecules and substances made up of a single type of molecule are called compounds.  A substance made up of more than one type of molecule is called a mixture.

Atomic and molecular masses are specified on a scale that’s compared to Carbon 12.  The distinction between solid, liquid and gases can be attributed to the strength of the attractive forces between the atoms and molecules and depends on their average speed.

Temperature is a measure of how hot or cold a body is.  Thermometers are used to measure temperature on the Celsius, Fahrenhiet and Kelvin scales.  Two standard points on each scale are the freezing point of water, which is zero degrees Celsius, 32 degrees Fahrenhiet, and 273 Kelvin, and the boiling point of water which is 100 degrees Celsius, 212 degrees Fahrenhiet, and 373 degrees Kelvin.  A change in temperature of one Kelvin equals a change of one Celsius degrees or 9/5 Fahrenhiet degrees.

The change of length, L, of a solid when its temperature changes by an amount, T, is directly proportional to the temperature change and to its original length, L_0. That is L is equal to alpha L₀ T, where alpha is the coefficient of linear expansion.

The change in volume of most solids, liquids and gases is proportional to the temperature change and to the original volume, V₀, where V is equal to beta V₀ T.  The coefficient of volume expansion, beta, is approximately equal to 3 times alpha for solids.  Water is unusual because unlike most materials whose volume increases with temperature, its volume actually decreases as the temperature increases from 0 degrees Celsius to 4 degrees Celsius.

Kinetic Theory of Gases

According to the kinetic theory of gases, which is based on the idea that a gas is made up molecules that are moving rapidly and at random, the average kinetic energy of the molecule is proportional to the Kelvin temperature.  At any moment, there exists a wide distribution of molecular speeds within a substance.

Heat

Thermal energy or internal energy refers to the total energy of all the molecules in a body.  Heat refers to the transfer of energy from one body to another because of a difference of temperature.  Heat is thus measured in energy units such as Joules.  Heat and thermal energy are also sometimes specified in calories or kilocalories where one calorie is equal to 4.18 Joules, and one calorie is the amount of heat needed to raise the temperature of one gram of water by 1 degree Celsius.

Heat Capacity

The specific heat capacity, C, of a substance is defined as the energy or heat required to change the temperature of unit mass of substance by 1 degree.  In the equation, Q=mc T, where Q is the heat absorbed or given off, T the temperature rise or decline, and m, the mass of the substance, that is Q=mc T.  When heat flows within an isolated system, the heat gained by one part of the system is equal to the heat lost by the other part of the system.

Calorimetry

This is the basis for calorimetry, which is the quantitative measurement of heat exchange.  An exchange of energy occurs without a change in temperature whenever substance changes phase.  This happens because the potential energy of the molecules changes as a result of the changes in the relative positions of the molecules.

Heat of Fusion

The heat of fusion is the heat required to melt one kilogram of a solid into the liquid phase.  It is also equal to the heat given off when the substance changes from liquid to solid.  The heat of vaporization is the energy required to change one kilogram of a substance from the liquid to the vapor phase.  It is also the energy given off when the substance changes from vapor to liquid.

Heat Transfer

Heat is transferred from one place or body to another in three different ways.  In conduction, energy is transferred from higher kinetic energy molecules to a lower kinetic energy neighboring molecules when they collide.  Convection is a transfer of energy by the mass movement of molecules over considerable distances.  Radiation, which does not require the presence of matter, is energy transfer by electromagnetic way, such as from the sun.

All bodies radiate energy in an amount that is proportional to their surface area and to the fourth power of their Kelvin temperature.  The energy radiated or absorbed also depends on the nature of the surface, dark and absorbing versus brightly reflecting, which is characterized by the emissivity.

The first and second laws of thermodynamics

The first law of thermodynamics states that the change in internal energy of a system is equal to the heat added to the system, Q minus the work, W, done by the system.  This is simply a restatement of the conservation of energy and it’s found to hold for all types of processes.

The second law of thermodynamics can be stated in several equivalent ways.  One, heat flows spontaneously from a hot object to a cold one but not the reverse.  Two, there can be no 100% efficient heat energy.  That is, one that can change a given amount of heat completely into work.  And, three, natural processes tend to move toward a state of greater disorder or greater entropy.  Entropy is a quantitative measure of the disorder of the system.  From statistical point of view, the most probable state of a system is that with the most entropy or disorder.

Vibrations and waves

A vibrating object undergoes simple harmonic motion if the restoring force is proportional to the displacement.  In other words, it obeys Hooke’s law.  The force constant, K, is the ratio of restoring force to the displacement.  The maximum displacement is called the amplitude.  The period, T, is the time required for one complete cycle back and forth and the frequency, F, is the number of cycles per second.  They are related by F=1/T, the period.  The period of vibration for a mass, m, on the end of a spring is given by the following relationship.  T=2 pi square root quantity m/K.

Harmonic Motion

Simple harmonic motion is sinusoidal, which means that the displacement as a function of time follows a sine or a cosine curve.  A simple pendulum of length, L, approximates simple harmonic motion if the amplitude is not too great.  Its period is given by, T=2 pi the square root of l/g, where g is the acceleration due to gravity.

Resonance

During a vibration, the energy continually alternates between kinetic and potential.  When friction is present, the motion is said to damped.  The displacement decreases in time and the energy is eventually all transformed to heat.  When an oscillating force is applied to a system capable of vibrating, the amplitude of vibration is very large if the frequency of the applied force equals or nearly equals the natural frequency of vibration of the object.  This is called resonance.

Episode 24: Doctor Dan gives part 2 of his Cancer lecture series available in full at www.Medical-Mastermind-Community.com.

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Cancers and Associated Diseases – Part II

Xeroderma pigmentosa – sun exposed areas, auto recessive, can cause all skin cancers (BCC, SCC, and melanomas), and the defect is in DNA repair enzymes. Other DNA repair defects are associated with BRCA1 and BRCA2, p53, they splice out the defects, this group is called the chromosomal instability syndromes – Wiskott Aldrich, Blooms, Ataxia Telangiectasias, and Fanconi’s, all have probs with DNA repair.

Basic rule of thumb for BCC and SCC:

• Upper lip and up is basal cell carcinoma;
• lower lip and down is squamous cell

(therefore, lesion on lower lip = sq cell; lesion on upper lip = basal cell)

Example: inside nose is BCC, b/c above the upper lip

Example: keloid – sq cell carcinomas and 3rd degree burns and sq cell carcinoma developing in areas of drainage from the sinus and ulcer that doesn’t heal from antibiotics. So, wherever there is constant irritation, and division of cells related to irritation, there is an increase susceptibility to cancer. This does not hold true for scar cancer tissue related cancers of the lungs or adenocarcinoma (just applies to things on the skin – ie burns and draining of sinus tracts). Only bacteria assoc with cancer? H. pylori – adenocarcinoma and low grade malignant lymphomas.

XII. Grade vs Stage

A. Grade = what does it look like? The term well differentiated means that the tumor is making something like keratin or glands, and if it’s identifiable it’s called low grade. When the cells are anaplastic, poorly differentiated under the microscope, and if you cannot tell what it is, then it’s called high grade.

Example: sq cell carcinoma can see keratin pearls; can ID it, so it’s a low grade cancer.

Example: see gland like spaces, can ID so its low grade

B. Stage = (TNM) MC staging system; goes from least imp to most imp (TNM)

Example: breast cancer with axillary node involvement; therefore, the N=1, but the “M” is worse, b/c it indicates that cancer has spread to other organs like bone, etc. Just b/c it goes to lymph nodes doesn’t mean it is the most imp prognostic factor.

T=size of tumor; if tumor is over 2 sonometers, it has a chance of mets

N=nodes (next most imp for prognosis)

M=mets outside of nodes (most imp prognostic factor)

Stage is more important than grade for prognosis; and within staging, M is the most imp factor for prognosis.

Example: pt with prostate cancer, which of following has it the worst? The answer choices were cancer limited to prostate, it went into seminal vesicles, it involved the wall of bladder, went to lymph nodes, or bone? Answer = bone (bone represents the “M” of the TNM system – this is stage 4 by definition=mets)

Example: a slide of a colon cancer and a lymph node: what is most important – size of tumor or lymph node involvement? Lymph node. If it was also in the liver, what is most imp? Liver specimen is the most imp prognostic factor.

XIII. Host defenses – most important is Cytotoxic CD8 T cell

Others – NK cells, Ab’s, macrophages, type 2 HPY. In hospital, they look for altered MHC class I Ag’s in the cancer pt, b/c cancer wants to kill T cells; they do this by putting in perforins, which activate  caspasases, and this leads to apoptosis (the signal, from the perforins, activate the caspasases, which have proteases, which break down the nucleus and mitochondria, and cell dies, without any inflammatory infiltrate).

XIV. Other diseases seen in malignancy:

A. Cachexia – cause is TNF alpha; it is irreversible. Once you see a pt with disseminated cancer about to go into catabolic state, can give then total nutrition, but still won’t help. (Will not get muscle mass back, and this is due to TNF-alpha)

B. Many hematologic causes of anemia seen in malignancy

MC anemia in malignancy is Anemia of chronic disease (this is the overall most common)

Colon cancer: left side obstructs w/ right side bleeds; if you have RT side bleed in colon cancer, Fe def anemia is very common.

Mets to BM and replace BM. Or, use chemotherapy drugs that are cell cycle specific or cell cycle nonspecific – they wipe out the marrow. Can have autoimmune mechanism with certain malignant dz.

C. Associations with disseminated cancers:

1. Most pts with disseminated cancers are hypercoagulable, meaning that they have a tendency for forming clots. Classic Example: a pt with painless jaundice, left supraclavicular node (this is a distracter), had light color stools, lesions that jump from one part of body to next – trousseau’s sign: a superficial migratory thrombophlebitis due to carcinoma of the head of the pancreas). Pancreatic cancers can ALSO mets to left supraclavicular node (virchow’s node), and often describe trousseau’s sign, which is a vascular problem in the veins that jumps from one place to the next.

2. Another common thing seen is disseminated cancers is thrombocytosis – an elevated platelet count. Other causes of thrombocytosis: Fe def, splenectomy (ie see scar on abdomen), TB, anemias. If you  cannot find any obvious cause of thrombocytosis then the cause is cancer. 40% of disseminated cancers are thrombocytosis. Or a do a stool guaic for colon cancer.

D. MCC fever in malignancy = gram neg. infection. An E. coli if you have an indwelling catheter; Pseudomonas if you have a respirator, staph aureus can also be the cause from an indwelling catheter, but this is gram “+”. MCC death in cancer = infection.

XV. Paraneoplastic syndromes

These are signs and sometimes symptoms saying that you may have an underlying cancer present. Its important b/c when you recognize the signs and symptoms, then you can catch the cancer before it metastasize.

MC Paraneoplastic syndrome = hypercalcemia

2 mechanism for hypercalcemia in malignancy:

1) mets to bone, produce a chemical (IL-1, PGE2, both of which activate osteoclasts) that produces lytic lesions in bone, and you get hypercalcemia

2) renal adenocarcinoma or squamous carcinoma of mainstem bronchus that sits there and makes PTH-like peptide and causes hypercalcemia b/c it acts like PTH and breaks down bone. This is Paraneoplastic, but it’s not the most common one.

Example: 2 black lesions – both are markers for gastric adenocarcinoma; usually under the arm – called acanthosis nigricans, and other is called seborrheic keratosis (these are not neoplasms); however, when  these suddenly develop overnight, you get multiple outcroppings, and the outcroppings is a phenotypic marker for gastroadenocarcinoma; this is easy to remember b/c 2 black lesions are markers from gastroadenocarcinoma.

Example: clubbing – inflammation beneath on the bone called periostitis; inflamm of underlying bone causes proliferation of the soft tissue around it, which leads to clubbing (called hypertrophic osteoarthropathy). Clubbing is not always assoc with cancer; also assoc with bronchiectasis, IBS. But, if it’s a malignancy, it is due to primary lung dz.

Example: least common collagen vascular dz, but the most often assoc with a certain cancer. They have an elevation of serum CK; this is dermatomyositis; raccoon eyes, so you see inflammation of skin and muscle; high assoc with leukemias, lymphomas and lung cancer. patches of knuckles – Goltrin’s patches (seen in dermatomyositis).

Example: vegetations (sterile) on the mitral valve – assoc with mucous producing cancers such as colon cancer; this is called marantic endocarditis-aka nonbacterial thrombotic endocarditis; they are not infections and these marantic vegetations are assoc with mucous secreting colon cancers. Can they embolize? Yes. You will need history to separate from rheumatic fever, but history will relate more to colon cancer (ie polyarthritis).

Example: hyponatremia or Cushing’s – cancer in the lung = small cell carcinoma, which is secreting either ADH or ACTH; also, for small cell, they are aput tumors, S-100 Ag positive, neural crest origin, neural secretory granules.

Example: Hypercalcemia or secondary polycythemia: renal adenocarcinoma (can make PTH like peptide and/or EPO).

Example: Hypoglycemia or secondary polycythemia: Hepatocellular carcinoma (they can make EPO or insulin-like factor).

Example: Hypocalcemia or Cushing’s: auto dominant, and the rare tumor marker that can be converted to amyloid (calcitonin) – medullary carcinoma of the thyroid.

XVI. Tumor markers

1. 2 markers associated with Testicular cancer – alpha feto protein (AFP) (which is really the albumin of a fetus) and HCG.
2. AFP is a maker for–yolk sac tumor (endodermal sinus tumor). So the tumors in kids are yolk sac tumors (alpha feto protein). AFP is also assoc with Hepatocellular carcinoma, increased in neural tube defects (must be on folate while pregnant to prevent neural tube defects). In Down’s syndrome AFP is decreased. Marker for malignancy in bone, assoc with monoclonal spike: Bence Jones Proteins (light chain Ig), assoc with Multiple Myeloma.
3. Tumor marker for prostate cancer: PSA; not sp for cancer b/c it can be also increased in hyperplasia; it is sensitive but not specific. If you do a rectal exam, it is not increased. PSA is NOT an enzyme; it is an Ag and is within the actual cell. It will not increase with a rectal exam.
4. Breast cancer (surface derived) – 15, 3.
5. CEA–125: Ovarian cancer
6. CEA –Ag for colon cancer; and sometimes used for small cell, and breast ca. CEA can be a part of an immune complex, and will get CEA: anti-CEA immune complexes which deposit in the kidney, and lead to nephrotic syndrome – this is diffuse membranous glomerulonephritis = MC overall cause of nephrotic syndrome. Many of these are related to malignancy b/c CEA can be the Ag that is deposits in the glomeruli.
7. Woman with a trophoblastic mole, what would you get? Beta HCG

Most Common Causes (MCC) of Cancer:

• What is MC primary tumor of the brain in kids? Cerebellar cystic astrocytoma (B9). It’s not medulloblastoma. All astrocytomas are B9 (if asked what is the most common malignant primary tumor, and then the answer is medulloblastoma, which derives from cerebellum). MC actual tumor of the brain – cerebellar tumor derived from astrocytes;
• MC childhood cancer = ALL leukemia (other childhood tumors include CNS tumors, neuroblastomas (in the adrenal medulla), Burkitts, Ewing’s (tumor of bone with onion skinning), embryonal rhabdomyosarcoma.)
• Adults: incidence:
• Woman: breast, lung, colon
• Men: prostate, lung, and colon
• Killers: lung is #1 in both (followed by prostate/breast and colon)
• 2nd MC cancer and cancer killer in men and women combined = colon
• Therefore, from age 50 and on, you should get a rectal exam and a stool guaic. After 50, MCC cancer of “+” stool guaic is colon cancer.
• MC gyn cancer: endometrial (#2 is ovarian, and #3 is cervix)
• Cervix is least common b/c Pap smear. When you do a cervical pap, picking up cervical dysplasia, not cervical cancer (therefore the ‘incidence’ isn’t the highest).
• B/c cervical pap smears; the incidence of cervical cancer has gone down significantly b/c the detection of the precursor lesion, cervical dysplasia. So, b/c cervical Pap smear, incidence of cervical cancer has gone down dramatically (picking up the precursor lesion); with mammography, the incidence of breast cancer decreases, same with PSA.
• MC Gyn cancer killer: ovarian (#2 = cervical, #3 = endometrial); therefore to remember, the MC has the best prognosis – endometrial is MC and has the best prognosis. What is the only known existing tumor vaccine? HBV …why? MC infection transmitted by accidental needle stick in the hospital = Hepatitis B. B/c viral burden of Hepatitis B is greater than any infection, even more so than HIV. So, with the Hepatitis B vaccine, you won’t get three things (1) Hepatitis B, (2) Hepatitis D (requires Hep B), and (3) hepatocellular carcinoma (related to Hepatitis B related cirrhosis).

How do you eradicate hepatocellular carcinoma? Vaccination (ie in the Far East).

Have you read the Health Care Reform Bill H.R. 3590? Come on, it’s only 2,409 pages! Doctor Dan has read it. Watch this video to learn all about it.

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H.R. 3590

On March 23, 2010, President Obama signed H.R. 3590, the most sweeping health care legislation bill in our nation’s history.

What is in the health care bill?

Doctor Dan will be teaching the contents of H.R. 3590 and what to expect in a non-political way at the 3rd Annual Medical School LIFE Conference in Dallas, Texas on May 29-30, 2010.

Episode 23: Doctor Dan interviews Naheeds Ali, M.D., who is a pre-nursing adviser and college professor.

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Pre-Nursing Advice

Over the years, I’ve had a lot of questions about other medical careers besides becoming a physician.

Today’s interview with Dr. Naheeds Ali covers a few basic pieces of pre-nursing advice:

1. Study your career field in advance from people who are doing it

2. Don’t assume financial security, even in the nursing profession

3. In your career choices, stay within your educational background

Non-Clinical Careers For Physicians

Dr. Ali gave some good insight into what physicians consider when they leave clinical medicine.

Here are some of the things doctors consider when they leave clinical medicine:

1. How the economy will affect physician careers

2. Love of teaching

Episode 22: Download all of the MCAT Podcasts now. Dr. Brett Ferdinand  teaches one of the seven Biological Sciences lectures.

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Now all of the MCAT science exams are available here: 

Download MCAT Podcasts

Dr. Brett Ferdinand has been teaching and authoring MCAT books and DVD’s for nearly 2 decades. Recently, he co-authored a book with Dr. Flowers, the father of MCAT Prep books (Silver Bullet MCAT).

Episode 21: This is a General Chemistry 101 overview for the MCAT. Get ready for more specific and detailed podcasts on a WEEKLY basis.

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Conservation of Mass

The Law of Conservation of Mass state that there are no detectable changes in mass in any chemical reaction.  This indicates that there are the same number of atoms of each types present after a chemical reaction as there were before the reaction.  A balanced equation shows equal numbers of each type of atom on each side of the equation and is, thereby, consistent with the Law of Conservation of Mass.

MCAT Equations (download complete list of MCAT equations)

Equations are balanced by placing coefficients in front of the chemical formulas for the substances involved in the reactions.  It is possible to predict the products of simple reactions by analogy to known reactions and by use of the periodic table.  Among the reactions, there are the followings:

One; combustion in oxygen in which an organic compound reacts with oxygen forming carbon dioxide, water and possibly other products depending on the composition of the compound.

Two; neutralization reaction in which an acid plus a base react to form water or another neutral compound and a salt.  There are precipitation reactions in which one of the products over reaction between two substances in solution is insoluble in the solution.  The coefficient in a balanced equation can be interpreted as either the relative number of formula units involved in the reaction or the relative number of moles.

Avagadro’s Number

A mole of any substance is Avogadro’s number, which is 6.02 x 10²³ of formula units of that substance.  The mass of a mole of atoms, molecules or ions is the formula weight expressed in grams.  For example, a single molecule of water, H₂O, weighs 18 amu, which are atomic mass units.  A mole of water weighs 18 grams.  The empirical formula, or simplest formula, of a substance expresses the composition in terms of the smallest possible set of whole number subscripts denoting the relative number of atoms.  The mole concept can be used to determine the empirical formula of a compound and calculate the quantities involved in chemical reactions.  In dealing with reactions between substances and solutions, it is convenient to employ the concept of solution concentration.

Molarity

Molarity is defined as the number of moles of solute per liter of solution.  Molarity serves as a conversion factor for interconverting solution volume and number of moles of solute.

Chemical equations and energy

We will look specifically at the energy and the first law of thermodynamics.  Energy can be measured in terms of the ability to accomplish work or transfer heat.  An object may possess potential energy because of its position relative to another object or because of its composition.  Thus, chemical energy is potential energy which can be released when the object undergoes a chemical change.  An object may possess kinetic energy because if it’s relative motion to another object.  The first law of thermodynamics also referred to as the law of conservation of energy states that in any change that occurs in nature, the total energy of the universe remains constant.

It is often convenient to consider one portion of nature called the system as separate from all the rest called the surroundings.  According to the first law of thermodynamics any energy gained by the system in a change must equal the energy lost from the surroundings.  Any process in which heat energy is lost to the surroundings is termed “exothermic”.  On the other hand, when heat energy is absorbed by the system from the surroundings, the process is termed “endothermic”.

Heat changes occurring at constant pressure are of special interest.  The heat gained or lost by the system in a process occurring at constant pressure is termed the enthalpy change, represented by the symbol delta H.  This quantity is negative for an exothermic process and positive for an endothermic process.

Enthalpy

Enthalpy is a state function, which means that the enthalpy of a system is determined by specifying its present condition and not by the details of how it came to be in that state.  If a particular overall change can be described as the sum of several individual changes then enthalpy change for the overall process is equal to the sum of the enthalpy changes associated with the individual steps.

Hess’ Law of Constant Heat Summation

This statement is known as Hess’s law of constant heat summation. In applying Hess’s law, it is useful to define the standard heat of formation of a substance, which is the heat change in the formation of a substance from the elements, all in the states in which they are most stable at the temperature of interest.  This is usually 25 degrees Celsius.

Using Hess’s law, the enthalpy change in any reaction can be described as the sum of the heat of formation of all the products, less the heat of formation of all reactants.  In solving problems dealing with enthalpy changes, it is important to keep the following points in mind.

First, the enthalpy change in a reaction, delta-H, is directly proportional to the amount of substance that reacts or is produced.  Secondly, delta-H for any reaction is equal in magnitude but opposite in sign to the value of delta-H for the reverse reaction.  Thirdly, the heat of formation for any element in its standard state is zero.

Quantum Numbers

Now, we shall look at the quantum numbers.  According to quantum mechanics, the state of an electron in an atom is specified by four quantum numbers-n, l, m_l and m_s.  The principle quantum number, n, can take any integer value-one, two, three, etc.  l, the orbital quantum number can take on values from zero up to n^-1. m_l the magnetic quantum number can take on integer values from ^-l to ⁺l.  And m_s, the magnetic spin quantum number can be either ⁺ ½ or – ½.

The energy levels in the hydrogen atom depend on n whereas in other atoms, they depend on n and l.  When an external magnetic field is applied, the spectral lines are split, indicating that the energy depends also on m_l.  Even in the absence of a magnetic field, precise measurements of spectral lines show a tiny splitting of the lines called fine structure, whose explanation is that the energy depends very slightly on the spin quantum number m_s.

Pauli Exclusion Principle

The arrangement of electrons in multi^-electron atoms is governed by the Pauli Exclusion Principle, which states that no two electrons can occupy the same quantum state.  That is, they cannot have these same set of quantum numbers n, l, m_l and m_s.  The electrons as a result are grouped into shells according to the value of n and subshells according to the value of l.  This shell structure gives rise to a periodicity in the properties of the elements.

Chemical Bonds

Now, we shall look at chemical bonds.  Ionic bonding results from the complete transfer of electrons from one atom to another with formation of a three dimensional lattice of charged particles.  The stabilities of ionic substances result from the powerful electrostatic attractive forces between an ion and all these surrounding ions of opposite charge.  They call anions are negative ions, while cations are positive.  These interactions are measured by the lattice energy.

Covalent bonding results from the sharing of electron between atoms.  The rules that govern this sharing are based on the stability of the noble gas electron configuration.  This is called the Octet Rule.  We can represent shared electron pair structures of molecules by means of Lewis structures, which show the sharing of electron pairs between atoms.

The sharing of one pair of electron produces a single bond.  The sharing of two or three pairs of electrons between atoms produces double and triple bonds, respectively.  It sometimes happens that a single Lewis structure is inadequate to represent a particular molecule.  But then an average of two or more Lewis structures does form a satisfactory representation.

Lewis Structures and Resonance Forms

In these cases, the Lewis structures are referred to as Resonance Forms.  It also sometimes happens that the Octet Rule is not obeyed.  This situation occurs mainly when a large atom is surrounded by small electronegative atoms, like fluorine, oxygen or chlorine.  In such instances, the large atom often has more than an octet of electrons.

The strength of covalent bonds increase with the number of electron pairs shared between two atoms.  In single bonds, the bond strings are generally higher between atoms of smaller size.  It is important to recognize that even in covalent bonding electrons may not be shared equally between two atoms.

Electronegativity

Electronegativity is a measure of the ability of an atom to compete with other atoms for the electrons shared between them.  Highly electronegative elements strongly attract electrons.  The electronegativities of the elements which show regular periodic relationship are an important guide to chemical behavior.  The difference in electronegativities of bonded atoms is used to determine of the polarity of the bond.

Another application of electronegativity is in the assignment of oxidation numbers which are formal whole number charges assigned to atoms in molecules and ions.  Although the oxidation numbers do not represent the real charges on atoms except in simple ionic substances, they are of great value in helping us to organize chemical facts and are in aid in balancing equations and in the naming of compounds.

Oxidation Number

Oxidation may be defined as the process in which an atom undergoes an increase in oxidation number.  Reduction is a process in which an element undergoes a decrease in oxidation number.  In an oxidation^-reduction reaction, both oxidation and reduction occur in such a manner as to balance the total increases and decreases in oxidation numbers.

Stoichiometry

Chemical bonds and shapes.  The three dimensional structures of molecules are determined by the distances between bonded atoms and by the directions of chemical bonds with the respect to one another around a particular atom.  The Valence shell electron pair repulsion model explains these relative directions in term of the repulsions that exist between electron pairs.

Electrostatic Repulsions

According to this model, electron pairs around an atom orient themselves so as to minimize electrostatic repulsions.  That is, they remain as far apart as possible.  By recognizing the unshared electron pair take up more space, i.e. they exert greater repulsive forces then shared electron pairs, it is possible to account for the departures of bond angles from the ideal^-like values and to explain many other aspects of molecular structure.  The shape of a molecule and the bond polarities determine whether or not a molecule will be polar.  The degree of polarity of a molecule is measured by its dipole moment.

The Lewis model for covalent bonding can be extended to account very nicely for the geometrical properties of molecules.  We can imagine that the atoms in a molecule are bonded to one another by electron pairs that occupy pairs of overlapping atomic orbitals.  The extent to which the atomic orbitals share the same region of space, called overlap, is important in determining the amount of stability that results from bond formation.

Sigma (Single) Bonds

The bonds directed along the internuclear axes are called sigma bonds, sigma bonds or single bonds.  It is possible to formulate orbitals on an atom that are directed toward each of the other atoms surrounding it by forming a hybrid orbital.  These orbitals are made up of mixtures of the familiar SPND atomic orbitals.  Depending on the particular number of other atoms bonded to an atom and their arrangement in space, a particular set of hybrid orbitals can be formulated that has the necessary directional characteristics.

For example, SP3 hybrid orbitals are directed towards the corners of a tetrahedron.  In addition to the sigma bonds which determine the geometry of the bonding around a particular atom, there are also pi bonds constructed from remaining unhybridized atomic orbitals.  Thus, double bonds consisting of a sigma and a pi bond, or triple bonds consisting of a sigma and two pi bonds may be formed.  In some molecules, the pi bond may extend or be delocalized over several atoms.

Delocalization of the pi electron in a cyclic structure, such as in benzene or throughout a plane, leads to a special stability.  The coming together of atoms to form molecules may be viewed also as the coming together of the atomic orbitals to from molecular orbitals.  Atomic orbitals may combine with one another in various ways.  The rules for combining atomic orbitals on atoms to form molecular orbitals allow us to account very well for the observed properties of the diatomic molecules formed by the first several elements of the periodic table.

Properties of gases

To describe the state or condition of a gas, it is necessary to specify four variables-pressure, temperature, volume, and the quantity of the gas.  Volume is usually measured in liters and temperature in the Kelvin scale.  Pressure is defined as the force per unit area.  It is expressed in the SI unit as Pascals, where one Pascal is equal to one Newton per meter squared, which in turn is equal to one kilogram per meter second squared.  Pressure can also be defined in millimeters of mercury.  One standard atmosphere of pressure equals 101.3 kilopascals or 760 millimeter of mercury.  A barometer is often used to measure the atmospheric pressure.

The ideal gas equation

PV=nRT

Where P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and t is the Temperature in Kelvin.

Most gases at pressures of about one atmosphere and temperatures of 300 Kelvin and above obey the ideal gas equation reasonably well.  We can use the ideal gas equation to calculate variations in one variable when one or more of the others are changed.

Boyle’s Law

For a constant quantity of gas at constant temperature, the pressure of the gas is inversely proportional to the volume.  That is Boyle’s law.

Charles’ Law

Similarly for a constant quantity of gas at constant pressure, the volume of a gas is directly proportional to temperature.  That is Charles’ law.

Dalton’s Law of Partial Pressures

In gas mixtures, the total pressure is the sum of the partial pressures that each gas would exert if it were present alone under the same conditions.  That is the Dalton’s law of partial pressures.  In all applications of the ideal gas equation, we must remember to convert temperature to the absolute temperature scale, in Kelvin.  It is important to be able to use the ideal gas equation to solve problems involving gases as reactants or products in chemical reactions.

Molecular Weight of Gas

From the gas density, rho, under given conditions of pressure and temperature, it is possible to calculate the molecular weight of the gas, where molecular weight will, therefore, be equal to rho rt/p, this can be derived from PV=nRT.  As long as you remember that the density is equal mass divided by volume.

Density = Mass / Volume

In calculating the quantity of gas collected over water, correction must be made for the partial pressure of water vapor in the container.

Kinetic Molecular Theory (analagous to Brownian Motion)

The kinetic molecular theory accounts for the properties of an ideal gas in terms of a set of assumptions about the nature of gases.  Briefly, these assumptions are that molecules are in ceaseless, chaotic motion, that the volume of gas molecule is negligible in relation to the volume of their container, that the gas molecules have no attracted forces for one another, and finally, that the average kinetic energy of the gas molecules is proportional to absolute temperature.

The molecules of a gas do not all have the same kinetic energy at a given instance.  Their speeds are distributed over a wide range.  The distribution varies with the molecular weight of the gas and with the temperature.  The root mean square speed varies in proportion to the square root of absolute temperature and inversely with the square root of molecular weight.  It follows that the rate at which a gas escapes or effuses through a tiny hole is inversely proportional to the square root of its molecular weight.

Non-Ideal Gases

Molecules in a real gas posses finite volume and, thus, undergo frequent collisions with one another.  These frequent collisions will limit the rate at which a gas molecule can diffuse through a space occupied by other gas molecules and determine the thermal conductivity of the gas.  The extent of non ideality of a real gas can be seen by examining the quantity PV over RT for one mole of a gas as a function pressure.  This quantity is exactly equal to one for an ideal gas at all pressures.

Real gas will depart from ideal behavior because the molecules possess finite volume or because the molecules experience attractive forces from one another upon collision.  The van der Waals equation is an equation of state for gases that attempts to correct the ideal gas equation to take into account the two properties of real gases.

Solutions-solutions are homogenous mixtures of atoms, ions, or molecules.  The relative amounts of solute and solvent in a solution can be described qualitatively-dilute or a concentrated solution, or quantitatively, as in weight percentage; molarity, which is moles per liter; molality, which is moles solute per kilogram solvent; normality, equivalence per liter; or mole fraction.  Mole fraction is the ratio of the number of moles of one component of a solution to the total number of moles of all substances present.

The extent to which a solute will dissolve in a particular solvent depends on the relative magnitudes of solute^-solute or solute^-solvent, and solvent^-solvent attractive forces, as well as the – it depends on the changes in disorder accompanying the mixing.  The rule, like dissolves like is found to be useful in rationalizing solubilities.  It is possible to chain the solubility of a solute by changing temperature and pressure.  If the solution process is endothermic, an increase in temperature promotes solubility.  With a gas, an increase in pressure promotes solubility.

Le Chatelier’s Principle

These effects can be understood in terms of Le Chatelier’s principle.  Substances that exist in solution as ions are called electrolytes.  Those substances that are completely ionized in solution are called strong electrolytes.  Reactions occur between electrolytes if an insoluble substance, a gas or a non^-electrolyte conforms.  Net ionic equations focus attention on the particular species that actually undergo some change during the reaction.

The presence of a solute in a solvent lowers the vapor pressure and the freezing point, and increases the boiling point of the solvent.  These changes are termed colligative properties.  The magnitude of the change depends on the total concentration of solute particles in solution, and not on there characteristics.

Acids and Bases

Acids and bases-an acid solution is created when a substance reacts with water in such a way as to increase the concentration of solvated hydrogen ions, which are represented as H⁺ or H₃O⁺.  The concentration of H⁺ is often expressed on the pH scale, where pH equals negative log concentration of hydrogen ions.  Solutions of pH less than seven are acidic.  Those with pH greater than seven are basic.

Ionization of Water

Water spontaneously ionizes to a slight degree, forming H⁺ and OH^-.  The extent of ionization is expressed by the ion product constant for water, which is Kw, which is equal to a concentration of a H⁺ times the concentration of OH^-, which is equal to 10 to the minus 14.  This relationship describes not only pure water but aqueous solution as well.  Because the concentration of water is effectively constant in dilute solutions, the concentration of water is omitted from this equilibrium constant expression as well as from others associated with reactions in aqueous solutions.

Bronsted-Lowry Theory

One can rely on the Bronsted-Lowry theory of acids and bases.  According to this theory, an acid is a proton donor, or a base is a proton acceptor.  Reaction of an acid with water results in the formation of H⁺ and the conjugate base of the acid.  Strong acids have conjugate bases that are weaker than water.  Such acids are strong electrolytes, ionizing completely in solution.  The common strong acids are HCl, HBr, HI, HNO₃, HClO₄, and H₂SO₄.  Weak acids are substances for which the reaction with water is incomplete and equilibrium is established.

Dissociation Constants

The extent to which the reaction proceed is expressed by the acid dissociation constant K_a.  Polyprotic acids are acids such as H₂SO₃ that have more than one ionizable proton.  Aside from the ionic hydroxides, such as NaOH, base is produced an increase of OH^- by reaction with water.  Strong bases have conjugate acids that are no stronger than water.  The common strong bases are the hydroxides and oxides of the alkali metals and alkaline earth.  Weak bases include H₂O, NH₃, amines, and the anions of weak acids.  The extent to which a weak base reacts with water to generate OH^- and a conjugate acid of the base is measured by the base dissociation constant, K_b.

Episode 20: Welcome to the MCAT Podcast series, where Doctor Dan will cover the actual science material required for the MCAT. Starting off with an overview of Biological Sciences topics, we’ll get increasingly more specific as time passes.

 MCAT Biology 101 [46:31] Play Now | Play in Popup | Download (12983)

Biology for the MCAT

Classes of Organic Molecules

Four major classes of organic molecules found in living organisms are carbohydrates, fats, proteins, and nucleic acids.

Condensation Reactions

Though these classes of molecule have different structure and function, they are built up of many similar building block molecules bonded together. In each case, building block molecules are combined by the removal of water, and this is called “condensation reactions.”

Condensation reactions are reversible. The complex organic molecules can be hydrolyzed into the simpler building blocks molecules with the addition of water. The basic building block molecules of carbohydrates are the simple sugars or monosaccharides.

Disaccharide Bonds

When two simple sugars are bonded together, a disaccharide is formed. When many simple sugars are bonded together in long chains, a polysaccharide is formed. Starch, glycogen, and cellulose are examples of polysaccharides.

The carbohydrates are an important energy source for all organisms. Lipids, the fats, and fat-like substances tend to be insoluble in water. Fats are made up of two building block molecules – glycerol and fatty acids. Phospholipids are derived from the fats. They are important constituents of cell membranes.

Peptide Bonds

The basic building block molecules of the proteins are amino acids. Amino acids are bonded together to form a protein by condensation reactions. The resulting bond is the peptide bond and the chains produced are polypeptide chains. The primary structure of each protein is the sequence and type of amino acids making up the polypeptide chains.

Because hydrogen bonds form between one amino acid and another, the chain assumes a stable regular shape known as the secondary structure. These regular molecules may in turn be folded into complicated globular shapes by weak attractions between the different R groups within the chain, thus forming the tertiary structure of the protein.

Nucleotide Bonds

Some globular proteins are made up of two or more polypeptide chains held together by weak bonds. The way these chains fit together determines the ordinary structure. Because the conformation of a protein depends on weak bonds, it is easily altered causing a change in biological function.

The building block unit of nucleic acids is the nucleotide, which is made up of a five carbon sugar attached to a phosphate group and to a nitrogen-containing base. Nucleotide units are joined together through condensation reactions between the sugar of one nucleotide and the phosphate group of the next.

There are four different nucleotides in each nucleic acid. It is the different sequences of the nucleotides that encode their hereditary information. The two types of nucleic acids, DNA and RNA, differ in their basic make up and in the number of strands in the molecule. We will be discussing this in greater detail later.

Free Energy and Enzymes

Chemical reactions that release free energy are exothermic or exergonic. Reactions that require the addition of free energy are endothermic or endergonic. In living systems, an exothermic reaction is usually coupled with an endothermic reaction. Although exothermic reaction proceeds spontaneously, initiating a reaction may require an activation energy.

Chemical reactions can be speeded up by heat, by increasing the concentrations of the reactants, or by providing the appropriate catalyst. In living systems, the catalysts are enzymes. Most enzymes are highly specific and each can interact only with those reactants or substrates that fit spatially and chemically into the active site of the enzyme.

Since the formation of the enzyme, substrate complex requires the enzyme and the substrate to be complementary. Anything that alters the shape of the enzyme will alter its activity. In addition to temperature and pH, many chemical substances can mask, block or alter the shape of the enzyme and its active site.

The Biological Cell

Now, let us discuss cells. The fundamental organizational unit of life is the cell. Most cells are very small and have a large ratio of surface area to volume so they can effectively exchange materials like oxygen, nutrients, and waste with the surrounding environment.

Plasma Membrane

Cells are bounded by a plasma membrane composed of lipids and proteins with many small pores. According to the fluid mosaic model, the plasma membrane consists of a bi-layer of phospholipids with their hydrophilic heads oriented towards the surfaces of the membrane and their hydrophobic tales toward the interior.

Protein Channels

The proteins are distributed both on the surfaces and in the interior of the membrane. The pores are thought to be bounded by protein. The distinctive properties of these proteins make the pore selective as to what can move through them. The cell membrane is an active part of the cell. It regulates the movement of materials between the ordered interior of the cell and their outer environment.

Passive Transport

This type of molecular passage from one side of a membrane to another requires no external energy. This is governed by charge and osmolality balance, which are intrinsic properties of solutions.

Diffusion

The general rule is that the net movement of particles of a particular substance is from regions of higher concentration to regions of lower concentration of that substance. This movement of particles is called “diffusion.” The plasma membrane is differentially permeable. It allows particles of some substances to pass through while excluding others.

Osmosis

The movement of water through a plasma membrane is called “osmosis.” Cell membranes are relatively permeable to water and to certain simple sugars, amino acids and lipid soluble substances. They are relatively impermeable to polysaccharides, proteins and other very large particles. Their permeability to small particles varies.

Facilitated Diffusion

The bilipid layer presents a barrier to substances insoluble in lipids. For such substances, some protein components of the membrane function as carrier molecules called “permeases.” In facilitated diffusion or passive transport, the substances being carried move with the concentration gradient and no energy is required.

Active Transport

In active transport, substances are moved against a concentration gradient; hence, the cell must expend energy. Sometimes substances are taken into the cell by an active process called “endocytosis.” The reverse sequence is called “exocytosis.” The cell membrane cannot completely regulate the exchange of materials.

A cell in a medium that is hypertonic, meaning higher osmotic concentration, relative to it tends to loose water and shrinks. Conversely, a cell in a hypotonic medium lower osmotic concentration relative to it tends to gain water and swell and may even burst. A cell in an isotonic medium, osmotic concentrations in balance neither gains nor looses appreciable water.

Sub-Cellular Components

Cell Walls

Fungi and bacteria have cell walls made not of cellulose but of other complex polysaccharide molecules.

Glycocalyx

Most animal cells have a cell coat of carbohydrates covalently bonded to protein or lipid molecules in the plasma membrane. This coat is called a “glycocalyx.” Eukaryotic cells have membrane-bound nucleus; whereas, prokaryotic cells – for example, bacteria – lack a membrane-bound nucleus.

Chromosomes

The nucleus contains the chromosomes which contain the genes. It can therefore direct the cell’s life processes. Separating the nucleus from the cytoplasm is a double nuclear membrane interrupted by pores.

Endoplasmic Reticulum

The nuclear membrane is continuous at places with the endoplasmic reticulum. The endoplasmic reticulum forms a system of interconnected membrane enclosed spaces. Sometimes the membranes of the endoplasmic reticulum are rough with ribosomes on their outer surfaces. When no ribosomes are present, the endoplasmic reticulum is smooth. Ribosomes are sites of protein synthesis.

The endoplasmic reticulum functions both as a passageway for intracellular transportation and as a manufacturing surface. The Golgi apparatus consists of stocks of membrane-bound vesicles that function in the storage, modification, and packaging of secretory products.

Cytoplasm

Mitochondria

Located within the cytoplasm are many other organelles. The mitochondria are the power houses of the cell. Chemical reactions within the mitochondria provide energy for the activities of the cell.

Lysosomes

Lysosomes are membranous sacs that function as storage vesicles for powerful digestive enzymes. They may act as the cell’s digestive system, hydrolyzing materials taken in by endocytosis.

Microtubules

Microtubules and microfilaments appear to function in intracellular movement and cell support. Microtubules also form the spindle of dividing cells and are the essential components of centrioles, cilia, and flagella.

Cellular metabolism

Cellular metabolism is a general term embracing the myriad of enzyme-mediated reactions of a living cell. It can be divided into two phases: anabolism – the building up phase – and catabolism – the breaking down phase.

Before the potential energy is stored in complex organic compounds, it can be used by the cell to do work. The compounds must be broken down in a series of chemical reactions and the energy transferred to ATP.

Glycolysis

The first series of reactions in the degradation of glucose is termed glycolysis. It is the breakdown of glucose to two molecules of Pyruvic acid with the production of two molecules of NADH, a net gain of two ATP molecules. This process common to all living cells is anaerobic, meaning oxygen is not needed.

Fermentation

The fate of the Pyruvic acid depends on the oxygen supply. In the absence of sufficient oxygen, the Pyruvic acid maybe reduced by NADH to form carbon dioxide and ethyl alcohol or lactic acid in a process called “fermentation.” NAD molecules, thus formed, are available to be reused in glycolysis.

Cellular Respiration

Under aerobic conditions, the Pyruvic acid can be further oxidized with the accompanying synthesis of ATP. This process is called cellular respiration.

Kreb’s Cycle

The process begins with the breakdown of two Pyruvic acid molecules to form two molecules each of acetyl coenzyme-A, carbon dioxide, and NADH. The acetyl coenzyme-A is fed into the Krebs’ citric acid cycle. In the course of this cycle, two carbons are lost as carbon dioxide, a molecule of ATP is synthesized, and eight hydrogens are removed and picked up by carrier compounds forming three molecules of NADH and one of FADH too.

Since one molecule of glucose gives rise to two molecule of acetyl coenzyme-A, two turns of the cycle occur for each molecule of glucose oxidized. The final stage of respiration involves the passage of the hydrogen electrons from the carrier molecules down a respiratory chain of electron transport molecules down to oxygen with which the electrons and hydrogen ions from the medium combine to form water.

Oxidative Phosphorylation

As the electrons are lowered step-by-step down the energy grade end, energy is released and some of it is used to make ATP. This process is called “oxidative phosphorylation.” The total number of new ATP molecules produced by the complete metabolic breakdown of glucose is usually 36 :

• 2 from glycosis
• 2 from the Krebs cycle
• 32 from the electron transport chain.

Cellular respiration captures about 38% of the energy of glucose and converts it into ATP. The rest of the energy is released mostly as heat. Most animals turned “poikilothermic” and all plants promptly lose most of this heat to their environment.

Temperature Regulation

The body temperature and metabolic rate of poikilotherms fluctuates with the environmental temperature. A few animals, homoeothermic maintain a constant high-body temperature. Their metabolic rate can accordingly be maintained at a uniformly high level.

Humans are examples of homeotherms. We will now examine circulatory and lymphatic systems. The closed circulatory system of the human is composed of a heart, arteries, veins, and capillaries. The actual exchange of materials between blood and other tissues takes place in the capillaries. The human heart is a double pump. Each side divided into two chambers—an upper atrium, which receives blood and pumps it into the lower chamber; and the lower ventricle which then pumps the blood away from the heart.

The Human Circulatory System

The right heart receives deoxygenated blood from all over the body and pumps it via the pulmonary arteries to the lungs where it picks up oxygen and gives up carbon dioxide. The oxygenated blood then returns to the left atrium by the pulmonary veins. This portion of the circulatory system is called the “pulmonary circulation”. The left ventricle pumps the blood into the aorta and its numerous branches from which it moves into capillaries where the exchange of materials takes place, then into veins and finally back via the superior or inferior vena cava to the right side of the heart.

This portion of the circulatory system is called the “systemic circulation.” The heartbeat is initiated when a wave of contraction spreads out from the SA node to the AV node, which sends excitatory impulses down the Bundle of HIS stimulating both ventricles to contract. During systole, the blood is forced out of the heart and into the arteries under high-pressure.

Blood Pressure

During diastole, the blood pressure in the arteries falls. One-way valves and skeletal muscle action aid in moving blood in the veins. When you hear that someone has a blood pressure of 120/80, which is normal – 120 represent the pressure in the arteries during systole in millimeters of mercury.

The 80 in 120/80 represents diastole, the blood pressure during diastole in millimeters of mercury. The movement of materials into and out of capillaries is governed by the balance between hydrostatic blood pressure and osmotic pressure. The lymphatic system helps maintain the osmotic balance of the body fluids by returning excess tissue fluid and proteins to the blood.

Lymph nodes act to filter up particles and also a site of formation/maturation of some white blood cells. Blood consists of plasma, the liquid portion and formed elements, which are the red blood cells, white blood cells, and platelets. Blood clotting is initiated when damage tissue and disintegrating platelets release thromboplastin, which converts the plasma protein, prothrombin into thrombin.

The thrombin then converts fibrinogen into fibrin which forms the clot; thus fibrin forms the clot. The erythrocytes contain the oxygen-carrying pigment hemoglobin, which transports oxygen from the lungs to the tissues.

Most carbon dioxide is carried in the form of the bicarbonate ion HCO3-. The leukocytes defend the body against disease and infection. Some leukocytes carry on phagocytosis. Others produce enzymes that detoxify dangerous substances, and still others produced antibodies that destroy or inactivate certain kinds of foreign substances called “antigens.”

The Endocrine System

The endocrine system, the tissues that produce and release hormones in animals are termed “endocrine tissues.” The hormones are secreted more or less directly into the blood, which then transports them to other parts of the body.

Insulin

The pancreas secretes insulin and glucagon, which regulate the blood sugar level. Insulin acts to reduce the blood glucose concentration. Glucagon causes an increase in the blood glucose concentration. The two adrenal glands located above the kidneys consist of an inner medulla and an outer cortex, which remain functionally distinct.

Epinephrine and Norepinephrine

The adrenal medulla secretes two hormones—adrenalin and noradrenalin. Both help to prepare the body for emergencies by stimulating reactions that increase the supply of glucose and oxygen to the skeletal and heart muscles. This is sometimes called the “fight-or-flight responds.”

Glucocorticoids and Mineralcorticoids

The adrenal cortex produces many different steroid hormones which may be grouped into three functional categories—one, those regulating carbohydrate and protein metabolism, the glucocorticoids; two, those regulating salt and water balance, i.e., the mineralocorticoids; and three, those that function as sex hormones.

Thyroxine

The thyroid gland is located just below the larynx. Two of the hormones it secretes are thyroxin and triiodothyronine. These two thyroid hormones stimulate the oxidative metabolism of most tissues in the body; thus, they increase the metabolic rate.

Calcitonin and Parathyroids Hormone

The thyroid also secretes calcitonin which prevents the excessive rise of calcium ions in the body. The parathyroids are four small P-like organs located on the surface of the thyroid. The parathyroid hormone, sometimes called “parathormone,” regulates the calcium phosphate balance between the blood and other tissues.

It acts primarily on the kidneys, the intestines, and the bones. The posterior pituitary is connected to the hypothalamus by a stalk. It stores and releases two hormones—oxytocin and vasopressin, which are produced in the hypothalamus and flow along nerves in the stalk to the posterior pituitary.

Oxytocin

The hormones are released upon nervous stimulation from the hypothalamus. Oxytocin stimulates the contraction of uterine muscles. Vasopressin causes constriction of the arterioles with a consequent rise in blood pressure. Vasopressin also stimulates the kidney tubules to reabsorb more water. The anterior pituitary produces many hormones with far reaching effects. Prolactin stimulates milk production by the mammory glands and also participates in reproduction, osmoregulation, growth, and metabolism of carbohydrates and fats.

Growth Hormone

Growth hormone promotes normal growth. The anterior pituitary also secretes a number of hormones that help control other endocrine organs. Thyrotrophic hormone stimulates the thyroid gland. Adrenocorticotropic hormone stimulates the adrenal cortex and the two gonadotropic hormones – FSH and LH – act on the gonads. The interaction between these glands and the anterior pituitary is an example of negative feedback. The activity of the anterior pituitary is in-tern regulated by the hypothalamus, which produces special peptide releasing hormones or releasing factors. These hormones are carried by portal system to the anterior pituitary where they stimulate its secretory activity. Therefore, the hypothalamus is the point at which information from the nervous system influences the endocrine system and is also one of the major sites of feedback from the endocrine system.

The Nervous System

The nervous system, the typical neuron consist of the cell body, which contains the nucleus, and one or more long nerve fibers call “axons” and “dendrites” that extend from the cell body. Sensory neurons lead from receptor cells. Motor neurons lead to effector cells and interneurons lie between the sensory and motor neurons.

Junctions between neurons are called “synapses.” A reflex arc is a simple neural pathway linking a receptor and an effector. Most somatic reflex arcs begin with a sensory neuron that conducts the impulse to interneurons in the spinal cord. These in turn synapse with motor neurons in the cord. And the impulses are conducted to the effectors usually skeletal muscles, which respond to the stimulus. Reflex arcs always inter connect with other neural pathways.

A nerve consists of a number of neuron fibers bound together. The autonomic nervous system consists of nervous pathways that conduct impulses from the central nervous system to various internal organs. These pathways usually involve to motor neurons. The autonomic nervous system regulates the body’s involuntary activities. There are two divisions of the autonomic nervous system—the sympathetic and parasympathetic systems. The sympathetic system associated more with fight-or-flight responses and the parasympathetic system associated more with vegetative responses.

Most internal organs are innervated by both with the two systems usually functioning in opposition to each other. A nerve impulse is a wave of electrochemical change moving along and their fiber. The potential stimulus must be above a particular threshold to initiate an impulse. If the axon fires, it will fire maximally or not at all. This is called the “all-or-none response.” The inside of a resting nerve fiber is negative with respect to the outside. When a fiber stimulated, sodium ions rush into the cell making the inside positively charge relative to the outside. And instant later, potassium ions, which are in higher concentration inside the cell, rush out of the cell restoring the original charge. This cycle of changes is called the “action potential.” A sodium potassium pump, ATPase pump, restores the original ion distribution.

When an impulse traveling along the axon reaches the synaptic boutton, it causes the synaptic vesicles to discharge their stored transmitter chemical into the cleft. The transmitter molecules diffuse across the cleft and alter the membrane potential of the next neuron. Synaptic transmission is slower than impulse conduction along the neuron.

Episode 19: Would you like to have an entire MP3 series dedicated to the MCAT? Well, that’s what I’m working on right now. Listen to this Renal Physiology lecture for a sample of what’s to come!

 MCAT Podcast Model [48:43] Play Now | Play in Popup | Download (6785)

Renal Physiology

A. ECF/ICF

ECF (1/3) = extracellular fluid of two compartments – vascular (1/3) and interstitial (2/3)

ICF (2/3) = intracellular fluid compartment

Example: how many liters of isotonic saline do you have to infuse to get 1 liter into the plasma? 3 Liters (2/3:1/3 relationship); 2 liters in interstial space, and 1 L would go to the vascular space; it equilibrates with interstial/vascular compartments.

B. Osmolality =

Measure of solutes in a fluid; due to three things: Na, glucose, and blood urea nitrogen (BUN) – urea cycle is located in the liver, partly in the cytosol and partly in the mitochondria; usually multiply Na times 2 (b/c one Na and one Cl). Normal Na is 135-140 range, times that by 2 that 280. For glucose, normal is 100 divide that by 18, let’s say it’s roughly 5, so that’s not contributing much. BUN:  located in the liver, part of the cycle is in the cytosol and part of it is in mitochondria. The urea comes from ammonia, that’s ammonia is gotten rid of, by urea. B/c the end product of the urea cycle is urea. The normal is about 12; divide that by 3, so we have 4. Therefore, in a normal person Na is controlling the plasma osmolality. To measure serum osmolality: double the serum Na and add 10.

C. Osmosis =

Among intracellular, intravascular, and interstitial spaces, 2 of these 3 are limited to the ECF compartment. One can equilibrate between ECF and ICF across the cell membranes – urea; therefore, with an increased urea, it can equilibrate equally on both sides to it will be equal on both sides; this is due to osmosis.

B/c Na and glucose are limited to the ECF compartment, then changes in its concentration will result in the movement of WATER from low to high concentration  (opposite of diffusion – ie in lungs, 100 mmHg in alveoli of O2, and returning from the tissue is 40 mmHg pO2; 100 vs. 40, which is bigger, 100 is bigger, so via diffusion, O2 moves through the interspace into the plasma to increase O2 to about 95mmHb). Therefore, in diffusion, it goes from high to low, while in osmosis, it goes from low to high concentration.

1. Hyponatremia

Example: In the case with hyponatremia – water goes from ECF into the ICF, b/c the lower part is in the ECF (hence HYPOnatremia); water goes into the ICF, and therefore is expanded by osmosis. Now make believe that the brain is a single cell, what will we see? cerebral edema and mental status abnormalities via law of osmosis (the intracellular compartment of all the cells in the brain would be expanded)

2. Hypernatremia

Example: hypernatremia – water goes out of the ICF into the ECF, therefore the ICF will be contracted. So in the brain, it will lead to contracted cells, therefore mental status abnormalities; therefore, with hypo and hypernatremia, will get mental status abnormalities of the brain.

3. Diabetic ketoacidosis

Example: DKA – have (1000mg) large amount blood sugar. Remember that both Na and glucose are limited to the ECF compartment. You would think that glucose is in the ICF but it’s not. You think that since glycolysis occurs in the cytosol therefore glucose in the ICF (again its not) b/c to order to get into the cell (intracellular), glucose must bind to phosphorus, generating G6P, which is metabolized (it’s the same  with fructose and galactose, which are also metabolized immediately, therefore, there is no glucose, fructose, or galactose, per se, intracellularly). So, with hyperglycemia, there is high glucose in the ECF, so water will move from ICF to ECF. Therefore, the serum Na concentration will go down – this is called dilutional hyponatremia (which is what happens to the serum sodium with hyperglycemia).

Therefore the two things that control water in the ECF are Na and glucose; but a normal situation, Na controls. Urea does not control water movements b/c its permeable, and can get through both compartments to have equal concentrations on both sides.

D. Tonicity =

Isotonic state, hypotonic state, and hypertonic state. We have all different types of saline: Isotonic saline, hypotonic saline (1/2 normal saline, ¼ normal saline, 5% dextrose in water), and  hypertonic saline (3%, 5%); normal saline is 0.9%. We are referring to normal tonicity of the plasma, which is controlled by the serum Na. These are the three types of tonicity (iso, hypo, and hyper). Serum Na is a reflection of total body Na divided by total body H20. For example: hypernatremia is not just caused by increased total body Na; it can also be caused by decreasing total body water with a normal total body Na, therefore there is an increase in serum Na concentration. It is really a ratio of total body Na to total body H20. To determine serum Na, just look at serum levels. With different fluid abnormalities, can lose or gain a certain tonicity of fluid.

1. Isotonic loss of fluid

– look at ratio of total body Na and water; in this case, you are losing equal amounts of water and Na, hence ISOtonic. This fluid is mainly lost from the ECF. The serum Na concentration is normal when losing isotonic fluid. ECF would look contracted. There would be no osmotic gradient moving into or out of the ECF. Clinical conditions where there is an isotonic loss of fluid: hemorrhage, diarrhea. If we have an isotonic gain, we have in equal increase in salt and water; ie someone getting too much isotonic saline; normal serum Na, excess isotonic Na would be in the ECF, and there would be no osmotic gradient for water movement.

2. Hypotonic solutions

A hypotonic solution, by definition, means hyponatremia. Hypoglycemia will not produce a hypotonic condition.

MCC of low osmolality in plasma is hyponatremia. How? Lose more salt than water, therefore, serum Na would be decreased. If losing more salt than water, kidney is probably the location of where/why it is happening. Main place to deal with sodium (either to get rid of it or to get it back) is in  kidney, esp when dealing with diuretics (Furosemide and HCTZ). The tonicity of solution you lose in your urine is HYPERtonic, so that’s how you end up with hyponatremia with a hypotonic condition. ECF concentration is low with hyponatremia, therefore the water will move into the ICF compartment. (Osmosis-remember low to high)

Syndrome of Inappropriate Andidiuretic Hormone (SIADH):

Example: If you gained pure water, and no salt, you have really lowered your  serum Na:  MCC = SIADH – in small cell carcinoma of the lung; you gain pure water b/c ADH renders the distal and the collecting tubule permeable to free water. With ADH present, will be reabsorbing water back into the ECF compartment, diluting the serum Na, and the ECF and ICF will be expanded. The ECF is expanded due to water reabsorption, and the ICF is expanded b/c it has a high concentration levels (its levels are not diluted). This can lead to mental status abnormalities. Therefore, the more water you drink, the lower your serum Na levels would be. The treatment is by restricting water. Don’t want to restrict Na b/c  the Na levels are normal. When ADH is present, you will CONCENTRATE your urine b/c taking free water out of urine; with absent ADH, lose free water and the urine is diluted. Therefore, for with SIADH, water  stays in the body, goes into the ECF compartment, and then move into the ICF compartment via osmosis. The lowest serum sodium will be in SIADH. On the boards, when serum Na is less than 120, the answer is always SIADH. Example: pt with SIADH, not a smoker (therefore not a small cell carcinoma), therefore, look at drugs – she was on chlorpropramide, oral sulfylureas produce SIADH.

Right Heart Failure and Hepatic Cirrhosis:

Example: Gain both water and salt, but more water than salt, leading to hyponatremia – these are the pitting edema states – ie RHF, cirrhosis of the liver. When total body Na is increased, it always produces  pitting edema. What compartment is the total body Na in? ECF What is the biggest ECF compartment? Interstial compartment. Therefore, increase in total body Na will lead to expansion of interstial compartment  f the ECF, water will follow the Na, therefore you get expansion via transudate and pitting edema; seen in right HF and cirrhosis.

• Example: hypertonic loss of salt (from diuretic) leads to hyponatremia
• Example: SIADH (gaining a lot of water) leads to hyponatremia
• Example: gaining more water than salt will lead to hyponatremia: pitting edema

3. Hypertonic state

A hypertonic solution, by definition means too much Na (hypernatremia) or hyperglycemia. Unlike in a hypotonic solution, you can have glucose contribute to this state. For example, a patient with DKA has a hypertonic condition, which is more common than hypernatremia. With hypernatremia,  what does ICF look like? It will always be contracted or shrunken.

Primary aldosteronsim

Gain more salt and water.

Diabetes insipidus

Lose pure water (vs. gaining pure salt in SIADH). If you lose more water than salt in the urine, you have osmotic diuresis – mixture. When there is glucose and mannitol in the urine, you’re losing hypotonic salt solution in urine.

Infant diarrhea

Hypotonic salt solution (adult diarrhea is isotonic), therefore, if baby has no access to water and has a rotavirus infection, serum sodium should be high because losing more water than salt, leading to hypernatremia. However, most moms give the baby water to correct the diarrhea; therefore the baby will come in with normal serum Na or even hyponatremia b/c the denominator (H2O) is increased. Treatment is pedialyte and Gatorade – these are hypotonic salt solution (just give them back what they lost). What has to be in pedialyte and what has to be in Gatorade to order to reabsorb the Na in the GI tract? Glucose b/c of the co-transport. With the co-transport, the Na HAS to be reabsorbed with glucose or galactose. Example: cholera, in oral replacement, need glucose to reabsorb Na b/c co-transport pump located in the small intestine. Gatorade has glucose and sucrose (which is converted to fructose and glucose).

Sweat

Hypotonic salt solution; if you are sweating in a marathon, you will have hypernatremia.

E. Volume Compartments

Physiologic response to hypovolemia:

Arterial blood volume is same as stroke volume and CO (cardiac output). When Cardiac Output decreases, all physiologic processes occur to restore volume. With decrease CO (ie hypovolemia), oxygenated blood will not get to tissues, and we can die. Therefore, volume is essential to our bodies.

1. Baroreceptors

We have baroreceptors (low and high pressure ones). The low pressure ones are on the venous side, while the high pressure ones are on the arterial side (ie the carotids and arch of aorta). They are usually innervated by CN 9 and 10 (the high pressure ones). When there is a decrease in arterial blood volume (decreased SV or CO), it will under fill the arch vessels and the carotid; instead of 9th or 10th nerve response, you have a sympathetic NS response, therefore catecholamines are released. This is good b/c they will constrict the venous system, which will increase blood returning to the right side of the heart (do not want venodilation b/c it will pool in your legs).

2. Catecholamines

Catecholamines will act on the beta adrenergic receptors on the heart, which will increase the force of contraction, there will be an increase in stroke volume (slight) and it will increase heart rate (“+” chronotropic effect on the heart, increase in systolic BP). Arterioles on the systemic side: stimulate beta receptors in smooth muscle. Diastolic pressure is really due to the amount of blood in the arterial system, while you heart is filling with blood.

3. Arterioles: The gatekeeper of tissue perfusion

Who controls the amount of blood in arteriole system, while your heart is filling in diastole? Your peripheral resistance arterioles – that maintains your diastolic blood pressure. So, when they are constricted, very little blood is going to the tissues (bad news); good news: keep up  diastolic pressure – this is important b/c the coronary arteries fill in diastoles. This is all done with catecholamines.

4. Renin-Angiotensin System

Renin system is activated by catecholamines, too; angiotensin II can vasoconstrictor the peripheral arterioles (therefore it helps the catecholamines). AG II stimulates 18 hydroxylase, which converts corticosterone into aldosterone, and stimulates aldosterone release, which leads to reabsorption of salt and water to get cardiac output up. With decreased SV, renal blood flow to the kidney is decreased, and the RAA can be stimulated by this mechanism, too. Where exactly are the receptors for the  juxtaglomerlur apparatus? Afferent arteriole. There are sensors, which are modified smooth muscle cells that sense blood flow. ADH will be released from a nerve response, and pure water will increase but that does not help with increasing the cardiac output. Need salt to increase CO.

Example: bleeding to death and there is a loss of 3 L’s of fluid – how can you keep BP up?  Give normal saline is isotonic therefore the saline will stay in the ECF compartment. Normal saline is plasma without the  protein. Any time you have hypovolemic shock, give normal saline to increase BP b/c it stays in the ECF compartment. Cannot raise BP with ½ normal saline or 5% dextrose; have to give something that  resembles plasma and has the same tonicity of plasma. Normal saline is 0.9%. Peritubular capillary pressures: you reabsorb most of the sodium in the proximal tubule (60- 80%). Where is the rest absorbed?; in  the distal and collecting tubule by aldosterone. The Na is reabsorbed into the peritubular capillaries. Starling forces in the capillaries must be amenable to it. Two starling forces: oncotic pressure (keeps fluids in  the vessel) and hydrostatic (pushes fluids out of vessel).

Example: When renal blood flow is decreased (with a decreased SV and CO), what happens to the peritubular capillary hydrostatic pressure? It decreases. Therefore, the peritubular oncotic pressure is increasing (ie the force that keeps fluids in the vessel), and that is responsible for reabsorption of anything into the blood stream from the kidney. This is why PO (peritubular oncotic pressure) > PH (hydrostatic pressure of peritubular capillary), allows absorption of salt containing fluid back into blood stream into the kidney. Tonicity of fluid reabsorbing out of proximal tubule is isotonic (like giving normal saline). ADH is  reabsorbing isotonic salt solution, but not as much as the proximal tubule. ADH contributes pure water, therefore, with all this reabsorption you have an isotonic sol’n add the ADH effect and the pt becomes  slightly hyponatremic and hypotonic, therefore absorbs into the ECF compartment when there is a decreased CO.

Opposite Example: increased SV, and increase arterial volume, will lead to stretch of baroreceptors (innervated by 9th and 10th nerve), and a parasympathetic response will be elicited, instead of a sympathetic response. There will not be any venuloconstriction nor any increase in the force of contraction of the heart. This is fluid overload; therefore we need to get rid of all the volume. There is increased renal blood  flow, so the RAA will not be activated. Fluid overload does not ADH be released. The peritubular hydrostatic pressure is greater than the oncotic. Even of the pt absorbed salt, it wouldn’t go into the blood stream, and it would be pee’d out. Therefore pt is losing hypotonic salt solution with increased in arterial blood volume. Need to know what happens if there is decreased CO, what happens when ANP is released from the atria, and give off diuretic effect; it wants to get rid salt. ANP is only released in volume overloaded states.

Example: pt given 3% hypertonic saline: what will happen to osmolality? Increase. What will that do to serum ADH? Increase – increase of osmolality causes a release of ADH.

Example: What happens in a pt with SIADH? decreased plasma osmolality, high ADH levels.

Example: What happens in a pt with DI? no ADH, therefore, serum Na increases, and ADH is low How to tell total body Na in the pt: Two pics: – pt with dry tongue = there is a decrease in total body Na, and the pt with indentation of the skin, there is an increase in total body Na. Dehydration: Skin turgur is preformed by pinching the skin, and when the skin goes down, this tells you that total body Na is normal in interstial  space. Also look in mouth and at mucous membranes. If you have dependent pitting edema that means that there is an increase in total body Na.

SIADH – gaining pure water, total body sodium is normal, but serum Na is low; have to restrict water.

Right HF and dependent pitting edema – fluid kidney reabsorbs is hypotonic salt solution with a decreased CO (little more water than salt), therefore serum Na will low. Numerator is increased for total body sodium, but denominator has larger increase with water.

What is nonpharmalogical Rx of any edema states? (ie RHF/liver dz) – restrict salt and water What is the Rx for SIADH = restrict H2O. What is the Rx for any pitting edema state? Restrict salt and water. Pharmacological Rx for pitting water – diuretics (also get rid of some salt).

Episode 18: Over 6 years of Pre-Med Advising put online in one place! Doctor Dan organizes all of it and thoroughly describes how you can use this information to gain advantage over your competition.

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Ever feel lost in the Pre-Med grind, not knowing what to do next?

Have specific questions about the medical education process and get mixed answers all over the web that leave you feeling more confused and alone?
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Episode 23: Doctor Dan outlines Phase 1 in the Evolution Of A Physician-In-Training, part of his work/life balance initiative that seeks to prevent burnout among medical students and doctors.

SEE THE FULL REPORT HERE: Evolution of a Physician In Training: Effects of the medical education pipeline on personal and professional development.

Daniel M. Williams, MD

The 5 phases of a physician in training are general categories that describe the professional and psychological changes that students can expect to face. These have been organized into a Medical School Mindmap full of 179 peer-reviewed, scientific articles that describe the processes necessary to become the consumate physician.
The Phases are as follows:

1. Standing At The Precipice: The Premed Syndrome
2. Adaptation
3. Assimilation
4. The Let-Down
5. Reemergence

This area of research is meant to provide the foundation for a Health and Wellness Initiative among physicians. Physician Health is a top priority with Dr. Daniel Williams and each area is broken down inside the Medical Mastermind Community that has grown up around this ideal.

Here is an excerpt from the original draft:

Phase 1: Standing at the Precipice

Premedical students engaged in the early medical education pipeline frequently share similar goals and ambitions. The most commonly described premedical student traits are hard working, competitive, motivated, goal-oriented, altruism, and prestige-seeking (22-24). Fairly early in their premedical experience they begin to learn of the imperfection in the system.

A number of frustrations faced by these bright, enthusiastic students begin before even entering medical school. The challenges face by these future physicians can be categorized as follows:

1. Selection Bias. Learning that affirmative action exists without understanding the need for diversity can be a shock (143,145,156).
2. Academic Preparation. Realizing their undergraduate premedical and M.C.A.T. preparation may not actually predict how competent they will be as physicians can be disheartening (46,45,48).
3. Premedical Advising. Many students encounter premedical advisers, though wonderful guidance has been published for decades (11,15,17).
4. Admissions Criteria. The paradigm shift being birthed in premedical curriculum, which seeks to broaden one’s humanities background and foster empathetic relationships, is taking a surprisingly long time (4,6,27,28,30,31). The transition period as more medical schools are changing their admissions criteria and interview process can leave the premedical student confused about what is important in their preparation (184).

Because these sytstem-wide messages that contradict their altruistic nature, it is not surprising that the majority of students matriculating into medical school already have a well established ethical framework that is difficult to mold (26).

Further, two of the most historically trusted sources of information flat fail the premedical student attempting to learn about medical education. First, institutions of higher learning remain hyper-focused on grade point average though is associated with mere surface learning in medical school and the “MCAT Myth” of requisite rote memorization had been debunked by the mathematical application of Bloom’s Taxonomy (46). Second, nationally syndicated journalists yield influence in the ranking of “top medical schools”, but their method are ill-conceived; are unscientific; are conducted poorly; ignore the value of school accreditation; judge medical school quality from a narrow, elitist perspective; do not consider social and professional outcomes in program quality calculations; and fail to meet basic standards of journalistic ethics (32).

Sadly, the more idealistic and altruistic the nature of the unsuspecting premedical student, the greater the expectations in their career, and the greater the disappointment that comes in later phases in their evolution.

If we can be of any specific help to you, please feel free to contact us through the Ask A Doctor page.

Ping my blog

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Episode 22: Save time, learn different study techniques, relax with a system that you trust will work for you – Dr. Dan explains how you can get his Speed Reading Course for Medical School absolutely free.

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Episode 21: Interview with neurolinguistic programming expert Karen van Hook and test anxiety expert, and founder of Test Prep New York, Bara sapir.

Because no two people read the same MCAT passage exactly the same, it’s important to harness your internal dialogue to interpret passages, stay calm, and score higher – all at the same time. To learn more, visit www.testprepny.com.

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Episode 20: MCAT Prep like you’ve never heard before. Dr. Ferdinand and Dr. Dan discuss the MCAT from a physician’s point of view. With both doctors actively coaching premedical students, their synergy on this subject is nothing short of a Mastermind!

Dr. Ferdinand’s tells us about his not-so-secret performance on the MCAT and about his fatal error during planning his MCAT that caused him to not be able to even take the exam!

Listen to ALL of the expert interviews on the Medical School Podcast.

[More...]

The Association of American Medical Colleges administers the MCAT, accredits allopathic medical schools in the U.S., and manages the medical school application service.

The trend over the past 2 decades has been to emphasize thinking, organizing information, and problem solving rather than rote memorization.

In this episode, we two physicians discuss exactly why that is, what you can do to prepare, and ultimately whom you can trust when it comes to such an important exam – yourself!

Future episodes will cover

* Dr. Ferdinand’s 6 Steps to MCAT Preparation, which is remarkably similar to my 5-Step study method.

* Dr. Ferdinant’s interview with the “Father of MCAT Books” (Dr. Flowers)

* How a mastermind community can help premeds AND medical students

Listen in to learn more…

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Episode 19: Premedical Solutions that work, changing priorities as a physician, levels of Pre-Med commitment, and how to get the “I’m going to be a doctor” mentality.

In this interview with Randy Freeman, a Premedical University DVD Home Study Course graduate, we delve into 4 major areas:

1. How to get the “I’m GOING TO be a doctor” mentality
2. Levels of Pre-Med sophistication and commitment
3. Can you change your priorities later down the road, as a physician?
4. Premedical Solutions that work – study for the MCAT while in undergrad!

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Episode 17: What do people really score? And, how to interpret practice tests so you can accurately predict your score on the real MCAT.

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Announcements: * CD of the Month Club is now in it’s 21st month. The infrastructure for mass production is now in place.

Check out the new MCAT podcast interviews with GOLD STANDARD MCAT author, Dr. Brett Ferdinand

The Medical Mastermind Community is now live! Call me on our next pre-med conference call!

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A future doctor recently told me she made a 16% on a full-length Kaplan Practice MCAT. While that sounds bad, let’s put that score into perspective and look at how overall core knowledge deepens – specifically, how that is reflected in practice test scores. We’ll also delve into how to predict what score you’ll make on the actual MCAT.

This was my answer: “I sincerely understand your frustration and experienced it myself after taking the Kaplan course and my grades averaged out to be the same, having taken the MCAT 3 times. As a premed adviser now, I get this question a lot. You are not alone.” You have a multi-part topic, so let me take each item in turn: 1. What do people actually make on the MCAT? What is the MCAT cut-off?

Please give me real numbers! It’s on a bell curve so if you’ve taken statistics you know that they can separate out the elite by keeping people away from the 100% correct end of the spectrum. In fact, 60% raw correct answers can actually be solid and each test is weighted differently. See, each test is drawn from a bank and each question is weighted for it’s own usefulness.

There are a significant amount of test questions that are being assessed as keepers, but are not part of your grading. Here is where you can find the most recent REAL MD MCAT scores in Texas, Osteopathic MCAT Scores, and AMCAS MCAT Scores.

2. Do practice MCAT tests commonly show low scores? [Better yet, do these low practice scores really reflect how well I'll do on the real MCAT?] ANSWER: A full-length practice MCAT form a reputable source, such as Kaplan, AAMC, or Princeton review are reasonable reflections of how well you’ll do on the real thing. How to interpret your performance on these tests is actually more useful in real life. As a rule of thumb, scoring between 60-70% is actually average and approaching a solid score. Let me be clear, I’m not talking about little quizzes because the sample size of questions does not give you an accurate representation of your body of knowledge. Only pay attention to full-length, timed tests. I recommend you do between 3-7 of them, until you consistently get your overall average over 60% correct. If you expect to ace the MCAT you’ll want closer to an 80% average.

3. Is there another way to prepare for the MCAT? ANSWER: The best way I teach people to prepare for the MCAT is to start learning the material from the first day in undergraduate, if possible. Buy a respected review book and take notes in it while in undergrad and taking those classes. Write down revelations and pearls of wisdom as you begin to get insight into the different prerequisite disciplines – keep the book near you and review it periodically. Too many people only “review” for the MCAT, which often means RELEARNING material form 1.5 years ago or more and this is a tremendous waste of brainpower, not to mention the added stress has been shown to decrease long-term memory (cited resource is a meta-analysis). *******************************************************

Residency Spotlight: Surgery After 4 years of medical school, General Surgery takes 5 years. Many people sub-specialize after that and go to fellowships. Fellowships may be in GI Surgery, Pediatric Surgery, Trauma, or transplant. There are some training programs that are surgical which do not require a General Surgery residency first: Urology, Ob/Gyn, and Neurosurgery. Cheers, Doctor Dan

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Episode 15: PreMed Video Blog – watch in “Video Podcasts” on your iPod.

Hi!

I hope you enjoy the fact that I’m switching to video. You can still just listen on your iPod if you prefer, but I’ll be showing you tons of on-screen tutorials. You can see the video version by looking in the Video Podcasts section of your iPod directory (scroll through the videos…).

The MCAT questions, DVD course and FREE E-book are now available through the Medical Mastermind Community only. Ive launched a community website for all the fans that have built up around this movement in the past 2 years!

Cheers,

Dr Dan

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• 3rd Annual Medical School LIFE Conference will be May 29-30, 2010. The first one was a weekend series for the American Medical Student Association chapter at the University of Houston. Out of those conferences, the Pre-Med DVD Course was build as a sort of basic training. The following year charter members of the Medical Mastermind Community met for a weekend conference in which we led a Service Learning Project. The result was a grant proposal submitted to the National Institutes of Health to enrich students’ medical education journey and encourage service to the medically underserved.

• All 200 of the peer-reviewed, scientific journal articles were posted inside the web site for members only. They outline every facet of the medical education journey and correspond to the 5 Phases in the Evolution of a Physician in Training, which is my Physician Wellness Initiative. The idea is to increase awareness, receive validation, and try suggestions from others to find relief. So, just read the articles as you face the different ups and downs along the way.

• All of the medical school exams were also uploaded to the website. Previously they were only available as part of the CD of the Month Club, but we found it was inconvenient not knowing which tests covered specific material. The web outline breaks down each block exam by the topics covered on each set of tests. You can check out the navigation without logging in.

• Facebook 30-day challenge. If you’ll make a video about the Medical School Podcast or Speed Reading for Medical School course, I’ll give you a free, 30-day account tot he Medical Mastermind Community online – a $27.99 value. This includes our biweekly conference calls, from which video archives are now all updated.

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Episode 16: New medical mastermind community starting. Also volunteering, premed clubs  and committees may help you.

Call me, Doctor Dan, in one of our Medical Mastermind Support Groups and discover how to stay true to yourself during rigors of the medical education marathon.

Check the Medical Mastermind Group Schedule and login information. Hope to talk to you on the next call.

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Episode 14: Life after the medical school application? How to preempt the unexpected with a surprising amount of foresight!

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The medical school application is only one phase of your life. In this podcast and blog, I put this event in to the context of the entire medical school application process, give you some things to look forward to and prepare for, as well as direct you to where you can find an entire archive of tips like these all in one place.

By the time you submit your medical school application, you deserve a pat on the back. After all, you’ve completed the MCAT (in most cases), most of the medical school prerequisites and college, and overcome a large part of the mind game – talking yourself out of it. Many people change their mind and a growing trend is for ill informed pre-health advisers, with no qualification to speak on the subject, to discourage attending medical school.

From the time you submit your medical school application to the time you start your first day of medical school, there are a lot of activities that take place.
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Episode 13: Steps you can take NOW for balance in your medical career. You decide what’s important and implement a plan to keep it that way…
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Announcements:
Dropping a hint about my big project…got a high speed internet connection?

Also, for simplicity all CD’s will be mailed out during the last week of the month.

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Podcast topic

“If you had it to do all over again, what would you do different?”

This is a question I get a lot, in different forms. In fact my new big project I’m coming out with in the next few months is exactly geared toward answering this question – in all it’s detail.

See, feedback from my podcasting has made me realize that my experience with the premed obstacles you face is fodder for you cannon! I get just as excited with you as I coach students and reawaken their dreams of becoming a physician.

The biggest tips I can think of to answer this question with brevity are the following:

1. As an undergrad, write out what my life’s priorities are. Establish from the beginning and keep the document handy for editing as time passes.

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Episode 11: From MCAT to licensing – Overview of the entire medical education process. MCAT, First Year of Medical School, USMLE – and beyond…

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Announcements:
Happy New Year!
It’s now been 9 months of podcasting and we have over 21,178 downloads. I’m very encouraged by your emails and support.

In that short amount of time, hundreds of your questions have been answered and organized into a mindmap. With your help we put together a comprehensive, individualized PreMed coaching program. Visit www.PremedicalUniversity.com for more information.

The PreMed CD of the month club now has a link on the right of MedicalMastery. There is room for 11 more people right now. First come, first serve. That link will only be available intermittently when seats are available.

Live Teleclinics now available. Sign up for the free PreMed eBook on MedicalMastery.com and you’ll also get email notification of upcoming teleclinics.

Submit topics in the online survey “Grill the Guru”. The Ebooks is 16 chapters emailed to you weekly with other, exclusive PreMed strategies and insider

advice also. In total, you’ll get over 3 months of PreMed email content that you can save, store, and search in your email service for years to come!

DON’T DELETE the emails.

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Podcast topic

The first teleclinic we did had a nice video slide that covered all the steps in the medical education process. The new website that will host the free teleclinics.

After you’ve mapped out when you’ll be finished with college and all of the prerequisites for medical school, the next available August would be your first potential entering month and year. Plan to take the Medical College Admissions Test the year before.

You can successfully back-schedule from this date all of the necessary preparations so that you have time to do everything you need.

The first year of medical school is perhaps the hardest of all. You will be forced to adopt different learning styles for different types of information on the fly. The focus is on how the body works normally.

FIRST YEAR CLASSES:
Biochemistry
Cell development and tissue biology
Community health
Epidemiology / biostatistics
Family medicine
Gross anatomy
Growth and development
Health care policy
Hematology
Histology
History of medicine
Immunology
Interviewing
Introduction to clinical skills
Medical ethics
Molecular biology
Physiology
Preclinical electives
Problem-based learning

The second year is when you learn what goes wrong with human physiology.

SECOND YEAR CLASSES:
Addiction medicine
General pathology

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