Above: Image © AlenaChe,iStockPhoto.com

What do hitting puberty, feeling hungry, and getting stressed have in common? They all involve hormones!

Hormones are messenger molecules in your body. Just like the bodies of other multicellular creatures, your body has organs that carry out special tasks. Your organs include your liver, brain, stomach and even your heart. All of your organs must work together. And how do they coordinate their activities? By communicating through hormones!

Did you know? All multicellular (many-celled) organisms - animals, plants, and even most fungi - need hormones to coordinate and control their growth and development.

You have lots of little glands in your body that are constantly producing hormones. For example, there’s the hypothalamus and pituitary gland in your brain. There’s the adrenal gland right above your kidneys. Even the testes in males and ovaries in females are hormone-producing glands!

Hormones are part of the endocrine system, one of your body’s communication systems. The endocrine system regulates slower, gradual changes in your body (like growth and puberty), as well as repetitive processes, like sleeping every night and feeling hungry. In contrast, fast changes are regulated by your nervous system (think pain, decisions, and reflexes).

Hormones are around to make sure processes in your body happen as they should. Here are a few examples of processes controlled by hormones, and the specific hormones that help them happen:

Growth hormone

As we develop from a small baby to a full-grown adult, our bodies undergo dramatic changes. We grow larger bones and more hair, we lose our baby teeth, we get bigger and stronger! These changes must happen in a controlled and connected process. Could you imagine what would happen if our bones got bigger while our skin and muscles stayed the same size?

Our bodies use hormone messages to control all these simultaneous actions. One such message is Human growth hormone. This hormone signals to your body that it’s time to grow larger! When you get stronger and see your muscles grow, it’s because they are responding to growth hormone in your body. Without it, you’d never grow.

Did you know? As a teen, you’re producing about twice as much Growth Hormone as an adult.

Above: Somatotropin, or Human Growth Hormone, is produced in your pituitary gland, which located in your brain. The signal spreads throughout the entire body, telling the body to grow.
Image © RCSB Protein Data Bank, Modified by Harley Gordon

Some people with growth deficiencies (such as Turner’s Syndrome and Prader-Willi syndrome) are given human growth hormone as a treatment. This lets them grow and develop as normal.

Did you know? In some countries (but not Canada) bovine somatotropin (rBST), also known as Cow Growth Hormone, is given to dairy cows to increase milk production.

Sexual development

Gonadotropins are hormones that control the sexual development of some vertebrates (animals with backbones). They signal your body to make more testosterone or estrogen, which in turn can affect how you develop physically. Gonadotropins increase drastically during puberty. That’s why teenage bodies go through a lot of changes!

The hunger hormone

Ghrelin is also known as the hunger hormone. Your body produces ghrelin when your stomach is empty. It’s part of why you feel hungry. When you’re full and your stomach is stretched, your body stops producing ghrelin and you don’t get that hungry feeling anymore. If you eat too quickly, your body doesn’t have the opportunity to let you know it’s full. Slowing down to eat allows ghrelin to send a message to your brain that you’re full. That way, you won’t overeat.

Hormonal changes

During time periods when your body changes quickly, your hormone levels change. You may have heard people talk about your hormone levels changing in puberty. But they change at other times, too - like when you’re a newborn baby or even before before birth! These rapidly changing hormone levels can affect you in a few uncomfortable ways. For example, in puberty, they can cause mood swings and exhaustion.

Good news, though: once we hit adulthood our hormones tend to stabilize quite a bit. However, dramatic changes like pregnancy can cause hormones to fluctuate drastically again!

Did you know? Melatonin is a hormone that lets us know when it’s time to sleep and time to wake up. Its levels go up every evening and help us fall asleep, then drop quickly when we awaken. As we get older, we produce less and less melatonin in the evenings. This could be why people sleep less soundly as they age.

Can you control your hormones?

Here’s an exciting fact about hormones: we can control some of them! For example, let’s look at the hormone cortisol. One of cortisol’s jobs to signal to your body that something stressful is happening. Have you ever done anything scary, like public speaking or rock climbing? If so, you may have felt some of the effects of increased cortisol. For example, you might feel your heart beating faster. Or you might have a nervous need to pee!

But if we continue to do the tasks that stress us out and scare us, the body releases lower and lower levels of cortisol, and eventually we don’t get as stressed doing these things as much as we once did.

To demonstrate this, scientists measured the cortisol levels of new skydivers. They found that as the skydivers gained experience, their cortisol levels decreased. Individuals who had never skydived before had their cortisol levels monitored for three subsequent jumps throughout the day. By the third jump, the cortisol stress response to skydiving had diminished.

Summing up...

So there you have it. Hormones are messages that different parts of your body send each other to coordinate their tasks. We have many different types of messages! It takes a lot of organs working together to run a body, but hormones and our endocrine system make it all possible. Sometimes our hormones change, but they are always around, and they help make us human!

Learn more

Stress and the Brain (2015)
CurioCity by Let’s Talk Science

What is estrogen? (2012)
CurioCity by Let’s Talk Science

Hormones and Obesity (2015)
CurioCity by Let’s Talk Science

The science of attraction (2017)
CurioCity by Let’s Talk Science

What’s love got to do with it? (2012)
CurioCity by Let’s Talk Science


Hormones (2018)
Hormone Health Network

Stress and Hormones (2011)
Indian Journal of Endocrinology and Metabolism

Hormonal mechanisms in the onset of puberty (1975)
Postgraduate Medical Journal

Growth Hormone and aging: A challenging controversy
(2008) Clinical Interventions in Aging

Web-based molecular graphics for large complexes (2016)
Protein Data Bank

The Vagus Nerve and Ghrelin Function (2014)
Central Functions of the Ghrelin Receptor

Adrenocortical Responses to Repeated Parachute Jumping and Subsequent h-CRH Challenge in Inexperienced Health Subjects (1997)
Physiology and Behavior (9)

How the hormones ghrelin and leptin affect appetite

The role of growth hormone in fetal development (2002)
Growth Hormone and IGF Research

Age-Related Decreases in Melatonin Secretion - Clinical Consequences (2000)
The Journal of Clinical Endocrinology & Metabolism

Harley Gordon

Born and raised up and down the coast of British Columbia, I developed my passion for science at a young age. Eventually I moved to Victoria B.C. where I studied Biology and Microbiology. Following that I worked for a time as a chemist developing novel agricultural products. With that knowledge I started my Masters in plant biochemistry at the University of Guelph! I conduct basic research on the overall metabolism of different small molecules in plants. When I’m not in the lab you can find me outside rock climbing, hiking, camping, canoeing… most things really. I try to take my passion for nature, science and exploration with me everywhere I go. I love showing people how complex biological processes can be broken down into various chemical reactions!

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