Medical School Physiology: The Most Important Class in Medical School

What Is Medical School Physiology?

Physiology is one of the most important classes you will take as a future doctor. In fact, it is also my favorite course so far in the first two years of medical school. I remember during orientation, the former dean of my school said that if you can only pick one medical school course to really know well, it would be physiology. That’s all fine and dandy but what is it?

The course delves into how the body works. You will learn about how the heart pumps the blood throughout the body, how the lung takes in oxygen, how the kidney filters out urine, and almost anything else you can think of that pertains to bodily functions. The course is a mixture of biology and physics. There will be quite a few calculations to do, so brush up on your math skills. If physics was your strong point on the MCAT like it was for me, the class will not be that bad. You may also have a lot of fun!

If you like looking at charts, you’ll get your fill in this class. There is a chart for almost everything. And do know them well because they are not only tested in class, but also on the boards.

medical school physiology - spirometry

The top left graph is a flow-volume loop which measures lung function. Learn this well because you will most likely have to interpret it when you’re in the hospital. (Psst… but if you look closely at the bottom, the machine already interpreted it for you. No need to thank me.)

Less Memorization Than the Average Medical School Course

But most important of all, you won’t have to memorize as much as other classes. That is what gets me so excited about physiology. You can reason your way to the answer. Let me give you an example. If someone’s kidney is not getting enough blood, how does that affect the blood pressure? Here is how you can arrive at the conclusion.

  1. The kidney is not getting enough blood, so it thinks the body has a low blood pressure. The lack of blood flow could be due to low blood pressure but it could also be due to a blockage of the renal arteries.
  2. As a result, the kidney will release renin.
  3. Renin is then converted to angiotensin I, which is then converted to angiotensin II. As a side note, ACE (angiotensin-converting enzyme) inhibitors block the conversion of angiotensin I to angiotensin II.
  4. Angiotensin II would then promote the sympathetic activity of the body and the release of aldosterone.
  5. Those would help raise the blood pressure.

So the answer is that a low blood flow to the kidney would result in an increased blood pressure. If you know this pathway, you can answer almost anything related to it. Salt retention (aldosterone), how to treat hypertension (ACE inhibitors), etc.

Granted, learning how the body works do take some memorization at first but it is much, much less than other classes (I’m looking at you, biochemistry and especially microbiology).

Physiology in My School

Part of the reason I liked this course so much is because the subject is interesting. Another reason is because almost all of my medical school physiology teachers were awesome. They taught well, so I went to all the classes. There was a certain teacher who sometimes deviated from a traditional lecture. I remember in one instance, she would have games during class. I also remember winning some home-baked goods from the game. And yet, even with games, I was still learning. Pretty much everyone in my school would agree with me that physiology is largely well taught.

How to Succeed in Medical School Physiology?

This was the only class where there was a cumulative final. So you cannot forget whatever you learned throughout the year.

I’m actually glad I took my own notes summarizing the lectures for this class. Note taking will require a lot of time, but it helps me understand the materials better. But in this course, condensing the lectures into my personal notes really paid off in terms of time, because it saved me a lot of time when studying for the cumulative final. I reviewed the whole course in two days.

How did I do? I honored this course.

There was one thing I did that was even better than summarizing the lectures: doing practice exams. I did practice exams before every test. As for the cumulative final, after the two days of review, I just kept doing practice questions. It was not too bad because I had my answers and explanations for the practice exams I did throughout the year. It is okay to review practice questions even if you have done them previously. Actually, it is highly encouraged. If you refer back to my medical school study tips, you can see that I strongly recommend practice exams. In fact, I developed the bulk of my study methods by studying for this class.

This was the only class where I printed out the slides and took notes on the print-outs. It was okay for the first block because I only had to read through a few hundred pages. But as the year progressed, I found it cumbersome if you want to refer back to the print-outs. There were just too many pages. In second block, I switched to note taking on my laptop. I actually went back and converted all the notes to the electronic format.

Going to class was really only required for the cardiovascular section because the teacher’s slides were mostly pictures. You had to go to class to get the explanations. But for every other block, going to class is not necessary. Considering how fun and how well taught the classes were, I did not want to skip.

Study Tips

  • go to class (especially for the cardiovascular section)
  • take notes to summarize the lectures
  • do practice exams

Additional Medical School Physiology Resources

I did not read any textbooks. I just used the teacher’s slides. But for those who need a book to reference to, lots of students use books written by Linda Costanzo, Ph.D.


When it comes to Costanzo medical school physiology books, you have two options: the textbook or the BRS book. You really only need one or the other, no need to get both.


If you like reading paragraphs, then go with Costanzo Physiology textbook. It is almost 200 pages longer than the BRS Physiology book but you can get a more complete explanation of the concepts. If you are like me and prefer just the main points, go with the BRS. At more than 300 pages, it still is quite substantial. Just remember, I did not use any books for this class. I’m just providing the best options if you feel you need them for succeeding in medical school physiology.

For the books that you will need, take a look at the medical school books section.

Hey, you! Do you want to know how an accountant, without a science background, made it through medical school without any difficulty? Do you want to know how I memorized a sea of information without cracking my skull in half and dumping the books into my brain? No, I did not slave away all night studying in the library either. If you want to know my complete study system, check out The Secret of Studying.

This article is part of the How to Survive Medical School series. Click on the link if you want more tips and hints about surviving academic hell.


  1. TheGrincH says:

    Unfortunately, at my college, the physiology department is saddled with bad teachers. As a result of that, my physiological knowledge is woefully lacking.

    • Alex Ding says:

      Hey Grinch,

      That is sad to hear, since physiology is quite important in medicine. But there is still hope. If you do practice questions and review them, understanding why each answer is right and wrong, you can teach yourself physiology. That is pretty much what I had to do for most of second and third year of medical school.

  2. Wellinton Chipadze says:

    dont separate your physiology from anatomy, let them work hand in hand,it helps you understand better. Take time to review what you read at the end of every week, attend tutorials and ask anything that you did not understand as you read. Practise a lot of questions and set others for yoself that you may work on them towards exams

  3. Lynn Webb says:

    If your physiology professor doesn’t have past tests to use for practice tests, where is the best place to find practice tests?

    • Alex Ding says:

      Hey Lynn,

      Ask the people in the years before you. Maybe they’ll have something lying around. Or at the least, they’ll tell you what you should focus on during your studies.

  4. I was wondering where you were accessing good practice exams? I am in med school and physiology has been kicking my butt bc there are so many concepts and I get them confused. I am in renal physio right now and will have an exam in 2 weeks, what advice can you give me? I greatly appreciate it!!

    • Alex Ding says:

      Hey Ana,

      I got my practice exams through classmates and upper years. Try asking around and maybe someone will point you in the right direction.

  5. Alia H. says:

    Why can’t the book be downloaded for free ?
    I don’t have a credit card ( form can’t be filled)
    Help please

  6. Laurnetta says:

    I’m taking medical physiology as a graduate student. The course is taught by a former medical school teacher, and he has assured us that his class will be the equivalent of a medical school course. Today in our first class meeting we talked about diffusion across the cell member. I’m confused about hypertonic, isotonic, hypotonic, iso-osmotic, hyperosmotic, and hypo-osmotic. We had to determine the final concentration and volume of a cell when given the initial conc. and vol. of the cell and the solution that the cell was in. Is there anyone that can help me with this? By the way today is 8/23/2017 @6:59pm and my next class meeting is 8/25/2017 @ 8:00am.

  7. Gladys wangare says:

    Am a first year at a medical college in kenya…i really hope this is going to be fun and intresting…
    Psst…(i hope i understand the course)😜

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