Mcat Hormones

Biology is the most tested subject on the MCAT. This makes sense since physicians need to know a lot of biology. The MCAT biology material is split between molecular biology and physiology. In this post, we will focus on the physiology, specifically hormones. You may recall learning about all of the different organ systems within the body. You might also recall learning about the important role of hormones in regulating all the organ systems. It probably took you a lot of effort to memorize all of the hormones and you will have to do it again. MCAT hormones are one of the most commonly tested topics on the exam. The good news is that you do not need to know hormones to the same depth as a college physiology class. Here, we discuss what exactly you need to know about MCAT hormones.

Endocrine System for the MCAT: Everything You Need to Know

Learn key MCAT concepts about the endocrine system, plus practice questions and answers

(Note: This guide is part of our MCAT Biology series.)

Part 1: Introduction to the endocrine system

Part 2: Classifying hormones

a) Peptide hormones

b) Steroid hormones

c) Tyrosine derivatives

Part 3: Endocrine glands and secreted hormones

a) Pancreas

b) Anterior and posterior pituitary glands

c) Thyroid and parathyroid glands

d) Adrenal cortex and adrenal medulla

Part 4: Hormonal axes

a) Hypothalamic-pituitary-adrenal (HPA) axis

b) Hypothalamic-pituitary-gonadal (HPG) axis

Part 5: High-yield terms

Part 6: Passage-based questions and answers

Part 7: Standalone questions and answers

Part 1: Introduction to the endocrine system

The endocrine system works with the nervous system to alter metabolism, guide reproduction, and regulate growth. In this guide, we will provide you with an overview of endocrine-based content you need to know for the MCAT. At the end of this guide, there is an MCAT-style practice passage and standalone questions to test your knowledge and show you how the AAMC likes to ask questions.

The MCAT requires memorization of multiple hormones, glands, and target cells (also called effectors). We’ll be presenting this information in a few different ways. When studying, it may be helpful to group hormones together based on glands that secrete them.

Let’s get started!

Part 2: Classifying hormones

When functioning correctly, the endocrine system maintains homeostasis in the body. In other words, hormones are released in response to a condition rather than to create one. For example, insulin is released in response to high blood sugar levels; it is not released to create low blood sugar. This mechanism of action is referred to as negative feedback. While positive feedback is a mechanism to stimulate a condition through an action, negative feedback seeks to lessen a condition through an action.

How does the endocrine system accomplish this? The endocrine system releases hormones into the body’s general circulation, most often through blood, to affect other cells or tissues at a distance. (This is in contrast to autocrine signaling, in which a signaling molecule is released to affect the same cell or tissue, and paracrine signaling, in which a signaling molecule is released to affect a neighboring cell or tissue.)

Hormones can be classified into three distinct types, based on their structure: peptide hormones, steroid hormones, and tyrosine derivatives.

a) Peptide hormones

Peptide hormones are derived from peptides: short amino acid chains linked together by peptide bonds (e.g., O=C-NH bonds). Peptides are essentially short proteins. Therefore, peptide hormones are generally polar and water-soluble, allowing them to move freely through the bloodstream. However, peptides cannot easily diffuse through the nonpolar cell membrane. Therefore, peptide hormones generally require the presence of a receptor on the surface of the cell in order to effect an action.

When the peptide hormone binds to the receptor, there are multiple ways the receptor may respond. The receptor may act as an ion channel or interact with other proteins to create an ion-channel effect. (You can find more information on this signaling in our guide on lipids and cell membranes.)

The MCAT will most likely test your knowledge of a specific receptor system known as a G-protein coupled receptor, or GPCR. Upon binding to the hormone, G protein-coupled receptors undergo a conformational change that releases a G-protein by exchanging a low-energy GDP for a high-energy GTP. The G-protein activates the secondary messenger “cascade,” allowing secondary messengers like cAMP or IP3 to initiate a “cascade” of reactions within the cell. These secondary messengers serve to greatly amplify the effect of the hormone, as the binding of a single hormone molecule on the surface of the cell can result in a much higher concentration of secondary messengers to be activated!

MCAT Hormones: What to Know

Biology is the most tested subject on the MCAT. This makes sense since physicians need to know a lot of biology. The MCAT biology material is split between molecular biology and physiology. In this post, we will focus on the physiology, specifically hormones. You may recall learning about all of the different organ systems within the body. You might also recall learning about the important role of hormones in regulating all the organ systems. It probably took you a lot of effort to memorize all of the hormones and you will have to do it again. MCAT hormones are one of the most commonly tested topics on the exam. The good news is that you do not need to know hormones to the same depth as a college physiology class. Here, we discuss what exactly you need to know about MCAT hormones.

What You Need to Know for the MCAT

If you talk to any student that has taken the new exam, they will tell you that MCAT hormones are a big deal. For each hormone, you need to know:

• What type of hormone it is (peptide, steroid, or amino acid derivative)
• What gland secretes the hormone
• What causes the hormone to be released
• What are the targets of the hormones
• What are the effects of the hormone on the targets

Let’s go over insulin as an example. Insulin is a peptide hormone produced by the pancreas and is released in response to increased blood glucose levels. Insulin acts globally by stimulating the majority of all the cells in the body to increase cellular intake of glucose. In the liver, insulin acts to stimulate glycogenesis (also occurs in muscle cells), glycolysis, and lipid synthesis as well as inhibit gluconeogenesis and lipolysis.

All of this is actually only a small percentage of what insulin actually does in the body. As with all science topics, knowing more about insulin can be helpful for the exam (such as how diabetes is the result of insulin resistance or low insulin production). However, you also don’t want to get bogged down with all the small details. You won’t need to know them to answer the MCAT hormones question. Remember, the MCAT only tests the basics. You can wait until medical school to learn about all the fascinating intricacies of hormones.

This is already a lot to memorize but, unfortunately, there is more. According to the content outlines for the MCAT, you also need to know:

• Hormonal regulation of metabolism
• Definition of endocrine gland
• Neuroendocrinology – relation between neurons and hormonal systems
• Cellular mechanism of hormone action
• Transport of hormones: blood supply
• Specificity of hormones: target tissue
• Hormonal control of reproduction
• Hormonal control of sweating, vasodilation, and vasoconstriction

We hope you get the point. MCAT hormones are a big deal. There are numerous ways that the exam can test these special compounds.

MCAT Hormones Practice Questions

To give you an idea of how the MCAT tests hormones, we have a couple practice questions for you to try. If you think you know the answers, go ahead and let us know by commenting below!

1. All of the following are functions of follicle-stimulating hormone in females EXCEPT:

A. initiating follicle growth.

B. stimulating the production of estrogen in the ovaries.

C. stimulating the production of progesterone in the ovaries.

D. inhibiting the production of gonadotropin-releasing hormone in the hypothalamus.

2. Which of the following compounds is secreted in response to elevated blood pressure?

C. Atrial natriuretic peptide

Hopefully you now have a better idea of what you need to know about MCAT hormones for the exam. Make sure to check out our other post MCAT Amino Acids: What to Know to learn more about key concepts tested on the MCAT!

Author

Ken is a former blog writer for Magoosh who left to focus on developing novel and effective ways to help students achieve success on the MCAT exam. View all posts