Endocrine Systems on the MCAT

Table of Contents

The endocrine system is vital for our bodies to function properly. Have you ever had trouble falling asleep? That’s the endocrine system to blame. It makes and releases hormones that regulate bodily functions such as sleeping, growing, and metabolizing. These hormones even control your mood. 

We’ll be introducing the endocrine system, some key terms and definitions, and things you should keep in mind as you prepare for the MCAT. 

Let’s get started!

Endocrine Systems on the MCAT: What You Need to Know?

The MCAT is largely more breadth than depth. This means that if you find yourself struggling to understand the endocrine system, you’re in luck. Only knowledge of introductory biology (of which the endocrine system is included) is necessary. 

Introductory biology accounts for 65% of the Biological and Biochemical Foundations of Living Systems section (Bio/Biochem) and 5% of the Psychological, Social, and Biological Foundations of Behavior section (Psych/Soc)

It’s hard to predict the exact number of questions about the endocrine system that will appear on the MCAT. However, you can expect it to appear in both the Bio/Biochem and Psych/Soc sections.

Important Sub-Topics – Endocrine Systems

The endocrine system is a network of glands that regulate your bodily processes using hormones. 

What is a gland? A gland is a type of organ that specifically makes and releases something. For the glands in the endocrine system, they make and release hormones. So all glands are organs, but not all organs are glands!

The endocrine system can be complicated, so let’s break it down into important sub-topics you can concentrate on.

1. Anatomy 

The anatomy of the endocrine system refers to the glands that make up the endocrine system. There are a good number of them, but check out the chart below for some basic information about their functions.




Connects the endocrine system to the nervous system and produces hormones that regulate the pituitary gland


Produces the hormone, melatonin, that regulates your sleep/wake cycle


Control the function of other endocrine glands


Produces hormones that control your growth and metabolism


Produce hormones that control calcium levels


Produce the hormone epinephrine (aka adrenaline) and control blood pressure, heart rate, and stress response


Produce estrogen, progesterone, and testosterone


Produce testosterone


Produce white blood cells that fight infection


Control blood sugar levels

Aside from the glands themselves, part of the anatomy is also considering the mechanism that controls the endocrine system itself - the feedback loops. 

The main goal of the endocrine system is to maintain homeostasis. In order to not release too much or too little hormones and throw homeostasis out of balance, negative and positive feedback loops help the endocrine system regulate itself. 

Negative feedback loops inhibit hormones from releasing, and positive feedback loops stimulate more hormones to release. 

For more in-depth content review on anatomy of the endocrine system, check out these detailed lesson notes created by top MCAT scorers. 

2. Hormones, the Basics

Hormones are chemical messengers that carry signals through your blood to target organs, muscles, and tissues. They tell your body what to do and when to do it. The glands in the endocrine system make most of the hormones in your body. 

For more in-depth content review on the basics and principles of hormones, check out these detailed lesson notes created by top MCAT scorers. 

3. Antagonistic Hormone Pairs

Antagonistic hormone pairs are pairs of hormones that serve opposite functions. One hormone signals to counteract the target outcome of the other hormone. One antagonistic hormone pair is insulin and glucagon. Insulin signals to increase blood glucose levels, while glucagon signals to decrease blood glucose levels. 

There are over 50 hormones in the body, but studying antagonistic hormone pairs allows you to make connections that will help you learn the content a little easier. 

For more in-depth content review on antagonistic hormone pairs, check out these detailed lesson notes created by top MCAT scorers. 

4. Sex Hormones

Sex hormones play an important role during puberty, where they signal secondary sexual development. Prior to puberty, sex hormones are also responsible for ensuring your body displays the proper reproductive development based on your sex chromosomes. 

For more in-depth content review on sex hormones, check out these detailed lesson notes created by top MCAT scorers. 

5. Other Hormones

As stated, there are a lot of hormones! Not all of them fall under the category of sex hormones, so here are 3 other notable hormones of various functions to keep in mind.



Growth hormones

Signals for muscle and bone growth


Regulates your sleep/wake cycle

Antidiuretic hormones

Increases blood pressure

For more in-depth content review on other hormones, check out these detailed lesson notes created by top MCAT scorers. 

6. Hypothalamic-Pituitary Interactions

The hypothalamic-pituitary interactions are when the hypothalamus stimulates the anterior and posterior pituitary glands to release hormones. The hypothalamus will release a bunch of hormones that travel to the pituitary gland and trigger the pituitary gland to release even more hormones. 

For more in-depth content review on hypothalamic-pituitary interactions, check out these detailed lesson notes created by top MCAT scorers. 

7. Adrenal Glands

The adrenal glands are an important part of the endocrine system. They store many essential hormones that tie in with the nervous system. For example, epinephrine (also known as adrenaline) regulates the short-term stress response. 

For more in-depth content review on adrenal glands, check out these detailed lesson notes created by top MCAT scorers. 

Key Terms and Definitions – Endocrine Systems

Here are some of the more important key terms and definitions to remember for this general guide of the endocrine system!



Endocrine system

A network of glands that secrete hormones. These hormones go on to regulate many bodily processes.


Chemical messengers that travel through the bloodstream to target organs and tissues.


A specific type of organ that secretes something. For the glands in the endocrine system, they secrete hormones.

Feedback loops

A way for the endocrine system to self-regulate. There is the positive feedback loop, which stimulates the secretion of hormones. There is also the negative feedback loop, which inhibits the secretion of hormones.

Additional FAQs – Endocrine Systems on the MCAT

What hormones are released from the hypothalamus – MCAT?

The hypothalamus’ main function is to act as a coordinator of other glands, mainly the pituitary gland. As such, many of the hormones the hypothalamus releases are to trigger the release of other hormones. For example, some of the hormones the hypothalamus releases are the growth hormone-releasing hormone (GHRH), the corticotropin-releasing hormone (CRH), and the thyrotropin-releasing hormone (TRH).

How do you remember the endocrine hormones?

The best way to remember the many hormones involved in the endocrine system is by first memorizing the glands that they release from. Once you have the glands and their functions memorized, the hormones will be much easier to recognize. Drawing a chart to visualize the hormones involved with each gland will also be extremely beneficial in cementing your knowledge of the connections between the glands and the hormones.

What are the 7 hormones of the endocrine system?

There are a lot of hormones involved in the endocrine system. But if you were to concentrate on 7, the major hormones would be the growth hormones, melatonin, thyroid stimulating hormone, adrenaline, insulin, glucagon, estrogen, and testosterone.

What are the 4 major hormones in the endocrine system?

All hormones produced and secreted by the endocrine system are essential for normal bodily functions. However, the 4 major hormones to keep an eye on are the growth hormones, insulin, estrogen, and testosterone.

Additional Reading Links – Study Notes for Endocrine Systems on the MCAT

For more in-depth content review about endocrine systems on the MCAT, check out these detailed lesson notes created by top MCAT scorers!

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