Adrenal Glands: Structure & Function

Adrenal Glands

You have two adrenal glands, which are hormone-producing glands located on top of the kidneys. You might recall from other lessons that hormones are chemical substances that tell your body what to do. Because of their small size and the way they sit on top of your kidneys, it looks like your kidneys are wearing the adrenal glands like stocking hats.

Hormones from these glands help you deal with scary, stressful, and exciting events in life, so let's take a look inside the glands to better understand how they help you throughout your day.

Adrenal Medulla

If you were to cut open an adrenal gland, you would notice that it has two parts. The middle area of the adrenal gland is called the adrenal medulla. It might help you recall this term if you think of 'middle' and 'medulla' as sounding about the same. Your adrenal medulla is thought to be linked to your nervous system, which gives you a bit of a clue as to how the adrenal gland helps you cope with stress.

Your nervous system helps you react to this scary situation by stimulating the adrenal medulla to secrete its hormones into your bloodstream.

One of these hormones is adrenaline, which is also known as epinephrine. Adrenaline is a hormone that helps rev up your body because it increases your heart rate, blood pressure, and blood sugar level. You've probably experienced a pounding heart when you have been scared or excited; this is partly due to adrenaline and helps you deal with short periods of stress. The heart pumps harder and faster in these types of situations to get more blood to your muscles.

We learned that adrenaline also increases your blood sugar level because sugar, also known as glucose, is what your body turns to for quick energy. When a lot of glucose gets dumped into your blood, it becomes readily available energy, just in case you need a little extra to outrun Big Foot.

Adrenal Cortex

Experiencing an adrenaline rush from being scared or excited is a short experience. After a few minutes, you calm down, and your heart rate returns to normal. But sometimes life hands us situations that make us feel stressed or scared for a long time. Maybe you have a huge test coming up in a few weeks, and you don't know how you will do on it, or your best friend moves away, and you have a hard time dealing with the loss.

When these types of long-term stress hit us, the outer cover of the adrenal gland, known as the adrenal cortex, gets called on to secrete its own hormones. The word 'cortex' means 'covering,' which makes this term easier to remember. We see that hormones from the adrenal cortex help you deal with long-term stress. When your body is under a lot of stress, it uses a lot of energy. The adrenal cortex hormones help you out by producing more of the glucose that your body needs for energy.

Of course, your adrenal glands are not all about stress; they also help out in other ways. For instance, other hormones from the adrenal cortex help you balance the amount of water and salt in your body. Your body contains a lot of water because your body cells need fluid to function properly. If this level gets too low or too high, it can be disastrous for your health. Water likes salt and tends to hang out with it. By keeping the right balance of salt in your cells, your cells are able to hold on to the right amount of water, so they kind of work together.

We also see that hormones from the adrenal cortex cause some of the changes seen in puberty that determine male and female characteristics. The interesting thing is that regardless of whether you are a guy or a girl, your adrenal cortex secretes a small amount of male hormones as well as female hormones throughout life.