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Adrenal Glands: Function, Cortex & Medulla

  • 0:07 Adrenal Glands
  • 0:53 Adrenal Cortex and…
  • 3:55 Adrenal Medulla and…
  • 4:53 Lesson Summary
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Lesson Transcript
Instructor: Rebecca Gillaspy

Dr. Gillaspy has taught health science at University of Phoenix and Ashford University and has a degree from Palmer College of Chiropractic.

The adrenal glands sit on top of your kidneys and are comprised of an inner medulla region that is enclosed by the outer adrenal cortex. Both portions of the adrenal gland secrete hormones that regulate body functions and help maintain internal balance.

Adrenal Glands

As we learn about the endocrine system, we see that there are bits and pieces of endocrine tissue scattered about in different regions of your body. We even see endocrine glands sitting on top of each of your kidneys. In this lesson, we will learn about these unique and powerful glands that hover over top of your kidneys, called the adrenal glands.

The adrenal glands are endocrine glands that sit right on top of the kidneys
Adrenal Glands on Top of Kidneys

When you look at a picture of the kidneys, it's almost like they are wearing hats. These 'hats' are actually your adrenal glands. We can define the adrenal glands as hormone-producing glands located on top of the kidneys. When you look at a picture of one of your adrenal glands, it looks like a single organ. However, if you were to dissect the gland, you would quickly see that it's more like two endocrine glands in one.

Adrenal Cortex and Corticosteroids

The outer portion of the adrenal gland is called the adrenal cortex. It secretes steroid hormones. Steroid hormones are a class of hormones that are made from cholesterol. In today's world cholesterol often gets a bad rap for being detrimental to heart health. But it's interesting to learn that cholesterol actually serves a number of purposes in the body. For instance, if you did not have cholesterol, you would not be able to produce the steroid hormones from the adrenal cortex.

Without these hormones, your body would have a hard time regulating fluid and electrolyte balance and maintaining homeostasis. This is because the adrenal cortex secretes three major groups of steroid hormones that are collectively referred to as corticosteroids. This is an easy term to remember because we see that the prefix 'cortico' refers to the cortex of the adrenal gland and that the word 'steroid' is contained in the term. Therefore, we see that corticosteroids are steroid hormones secreted by the adrenal cortex.

Hormones secreted by the adrenal glands help maintain homeostasis in the body
Adrenals Regulate Homeostasis

There are different kinds of corticosteroids that we see coming from the adrenal cortex. One kind is called mineralocorticoids. Mineralocorticoids are important hormones that help regulate the water and electrolyte balance in the body. The two most important electrolytes that are regulated are sodium and potassium. Because sodium and potassium are both minerals, it may help you to recall that mineralocorticoids are important in the regulation of minerals.

Glucocorticoids are another kind of corticosteroid that we see coming from the adrenal cortex. Glucocorticoids help regulate carbohydrate, fat and protein metabolism and have an anti-inflammatory effect on the body. It's thanks to glucocorticoids that we are able to cope with a wide range of long-term stressors. Glucocorticoid secretions will increase any time we deal with continual stress. Anything from the death of a loved one to prolonged fasting can stimulate the production of glucocorticoids.

In fact, one of the effects of glucocorticoids is to increase blood glucose levels so we have readily available glucose for energy. This fact may help you recall the term because glucocorticoids increase glucose. Also, because glucocorticoids have an anti-inflammatory property, synthetic glucocorticoids are often prescribed as drugs to treat chronic inflammatory disorders in many areas of the body, including the bowel, skin, bones and joints.

Synthetic glucocorticoids are prescribed to treat chronic inflammatory disorders
Synthetic Glucocorticoids

In addition to mineralocorticoids and glucocorticoids, we also see sex hormones secreted by the adrenal cortex. The sex hormones are steroid hormones produced by the adrenal cortex that influence male and female sexual characteristics. Regardless of whether you are male or female, your adrenal cortex secretes male sex hormones as well as a small amount of female sex hormones throughout life.

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