The human endocrine system is responsible for creating a lot of fascinating—and incredibly important—hormones.
Hormones are, simply put, chemical messengers that relay signals to your organs and tissues telling them what to do and how to function. If your body is producing sufficient levels of all the critical hormones, everything functions properly. But if your endocrine (hormone) balance is out of whack—with some too high and others too low—that’s when you start to see problems.
The human body produces a lot of hormones, far too many for us to dive into in just one post. However, below, we’re going to take a much closer look at the most important hormones and find out where they’re created and what aspects of your body they control.
These are two of the most important hormones in the human body because of the role they play in reproduction.
Testosterone is produced in the testicles, and progesterone in the ovaries. They’re sometimes called the “male” and “female” reproductive hormones.
Testosterone contributes to the production of muscle tissue, helps the male reproductive tissues to develop, promotes secondary sexual characteristics (such as the growth of body hair or the deepening of the voice), and strengthens the bones.
Progesterone plays a role in maintaining pregnancy, prepares the body for conception, regulates the monthly menstrual cycle, and contributes to the regulation of sexual desire.
Low progesterone levels can cause sleep loss, mood swings, headaches, and irregular menstrual cycles.
Low testosterone levels can cause fatigue, hair loss, muscle mass loss, and a low sex drive, among other symptoms.
Estrogen is a hormone critical to the healthy functioning of the body (both males and females), though women tend to have much higher levels of estrogen. Produced in the ovaries, estrogen plays a role in bone health, female reproduction, female development (of the hips, breasts, and pubic hair), blood clotting, and the menstrual cycle.
As women age, their bodies produce less and less estrogen. Over time, this can lead to frailer and more fragile bones, as well as osteoporosis. Other side effects of low estrogen include depression, hot flashes, weight gain, low libido, and mood swings.
Melatonin is one of the hormones responsible for regulating your sleep cycle. Produced in your pineal gland (located in your brain), it controls your internal body clock. Exposure to daylight decreases melatonin production, while prolonged darkness will increase melatonin production—essentially helping you fall asleep and wake up.
Interruptions to your natural sleep rhythm can impair melatonin production. Exposure to bright light (such as TV screens, computer screens, and other artificial light sources) at night can also interrupt the release of melatonin, making it more difficult for you to fall asleep.
Triiodothyronine (T3) and Thyroxine (T4) are produced in your thyroid gland, and they play a central role in regulating our energy (metabolic rate), weight, body temperature, the health of our skin and hair, and even hunger and digestion.
Excessive production of these hormones is called hyperthyroidism, while insufficient production (the more common condition of the two) is called hypothyroidism. Both can lead to a wide range of health problems, including metabolic issues, weight gain/loss, and fluctuating energy levels.
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Insulin is a hormone released by the pancreas as a means of regulating blood sugar. Essentially, insulin encourages your liver, organs, and adipose (fat) tissues to absorb glucose from your bloodstream in order to prevent a glucose excess.
Typically, “healthy” people are sensitive enough to insulin that the body responds quickly to its presence and absorbs the glucose as intended. However, the modern high-sugar diet can often lead to insulin resistance, because there is so much sugar in the bloodstream that the pancreas is constantly releasing insulin, and the body becomes less sensitive to it over time. This can lead to elevated blood sugar levels, and is a main contributor to pre-diabetes and diabetes.
Insufficient insulin production can also be a contributor to diabetes. If something stops the pancreas from producing enough insulin, that can lead to higher-than-normal (or healthy) levels of glucose in the bloodstream.
Cortisol is the “stress hormone” because when your body is stressed (in a situation where it feels under threat or in danger), it triggers a release of cortisol (along with adrenaline). Cortisol increases the availability of glucose (energy) in the bloodstream, enhances your brain’s ability to use that glucose, and makes sure your body has more of the nutrients and hormones needed to repair tissues—all of which put your body into the "fight or flight” state necessary for survival. Cortisol is literally our body’s survival mechanism.
Unfortunately, long-term stress (a common problem in our modern lives) can lead to chronically high levels of cortisol, which can lead to an elevated risk of health problems like depression, anxiety, cardiovascular disease, and obesity. If your body is “stuck” in the “fight or flight mode”, it won’t function normally, and this dysfunction can contribute to chronic health conditions.
Adrenaline works with cortisol to facilitate the “fight or flight” response. In cases of emergency (or high activity), it is secreted by the adrenal gland (located in the medulla) and certain neurons in order to initiate a rapid response by the brain and body. It facilitates fast thinking, increases the metabolic rate to ensure more energy is available, dilates your blood vessels so more blood can flow through the body, and increases stress response.
Typically, adrenaline levels will spike during periods of exercise, as well as any stressful or dangerous situations. After the danger has passed or the exercise has finished, adrenaline levels return to normal—or, in some cases, will even “crash”, leaving you feeling tired and drained.
Serotonin is called a “feel-good chemical” because of the effect that it has on the human brain. It’s critical for regulating—and elevating—mood, and plays a role in sleep, learning, memory, and even digestion and some muscle functions.
Sadly, in our modern lives with such high cortisol levels, the brain doesn’t typically produce enough serotonin. This can lead to migraine headaches, cravings, insomnia, and weight gain.
Human growth hormone, or HGH, is produced in the pituitary gland for the express purpose of helping the human body to grow. It’s critical for the production and regeneration of cells, and plays a role in metabolic health. Typically, HGH production is at its highest among children and adolescents, and decreases as you reach adulthood. However, some HGH is critical for the maintenance of healthy muscle, bone, and tissue cells.
Insufficient HGH in children and adolescents can lead to stunted growth. Insufficient HGH among adults can lead to wasting of the bones and muscles. Thankfully, in addition to HGH injections (medically recommended for children and teenagers failing to produce HGH), HGH can be naturally increased by exercise, diet, and healthy lifestyle.
The truth is that there are many more important hormones that we could discuss—including luteinizing hormone (LH) and follicle-stimulating hormone (FSH), oxytocin, prolactin, and glucagon—but these hormones listed above are the ones most critical to the healthy functioning of your body.
It’s worth being aware of these hormones, understanding what they do and how they affect your daily health, so that you can be watching for the signs that any hormone levels are dropping. Endocrine problems can have widespread and lasting consequences, so if you experience any, it’s worth seeking treatment as soon as possible.
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