Endocrine System

What is the Endocrine System?

You may not think about the endocrine system every day, but it plays a critical role in every cell, organ, and function in your body.

The endocrine system does everything from regulate sexual function to control your good moods and bad moods. It produces the hormones you need to stay functional every day.

To find out what the endocrine system is and how it works, keep reading!

What Is The Endocrine System?

The Endocrine System is a Collection of Hormone-Secreting Glands

The endocrine system, like your digestive system, is a collection of different organs. These organs work together as a system.

In this case, the organs which make up the endocrine system are glands. These glands secrete hormones into our bloodstream. Then, our blood carries those hormones to targeted organs throughout the body.

The main glands of the endocrine system include:

— Pineal Gland
— Pituitary Gland
— Pancreas
— Thyroid Gland
— Parathyroid Gland
— Hypothalamus
— Gastrointestinal Tract
— Adrenal Glands
— Ovaries (in Females)
— Testes (in Males)

Those who study the endocrine system are called endocrinologists, and the study of the endocrine system is called endocrinology.

Secondary Endocrine Organs

All of the organs listed above are specialized endocrine organs. Those organs have one main job, and that is to produce and secrete hormones into the bloodstream.

However, these aren’t the only organs which secrete hormones. Other hormone-secreting organs include the bone, kidney, liver, heart, and gonads. All of these organs, however, have secondary endocrine functions, and secreting hormones isn’t their primary role.

How Does Each Endocrine Organ Work?

Each endocrine organ works in different ways and secretes different hormones. Here’s a breakdown of how each major endocrine organ works:


The hypothalamus is found in the lower central part of the brain. Like most organs, it’s simply a collection of specialized cells. It acts as the main link between the endocrine and nervous systems. The hypothalamus essentially acts as the “boss” of the pituitary gland: it produces chemicals that tell the pituitary gland exactly what to do. These chemicals stimulate production of hormones in the pituitary.


The pituitary gland is tiny: about the size of a pea. But despite its small size, the pituitary gland has big effects on the body. The pituitary is called the “master gland” because, like the hypothalamus, it acts as a boss, sending chemicals to other parts of the endocrine system which active their production.

The pituitary gland produces all of the following hormones:

Growth Hormone: Stimulates the growth of bones and other body tissue

— Prolactin: Activates milk production in women who are breastfeeding

— Thyrotropin: Stimulates the thyroid gland to produce thyroid hormones

— Corticotropin: Stimulates the adrenal gland to produce hormones

— Endorphins: Endorphins are chemicals which travel to the nervous system, where they reduce feelings of pain.

— Sex Hormones: The pituitary indirectly manufactures sex hormones by signaling your reproductive organs to start making sex organs

— Antidiuretic hormone: Controls the balance of water in the body to ensure your cells stay hydrated

— Oxytocin: Oxytocin triggers contractions of the uterus when a woman is ready to have a baby

Either directly or indirectly, the endocrine system plays a critical role in dozens of important bodily functions.


The thyroid is another well-known organ of the endocrine system. It’s found at the front part of your lower neck and is shaped like a bow tie. Its main job is to produce two important hormones: thyroxine and triiodothyronine, both of which control the rate at which cells burn fuels from food to produce energy.

The thyroid won’t produce either hormone until it receives a chemical signal from the pituitary gland in the form of thyrotropin.

You’ve probably heard that weight loss has a lot to do with your thyroid gland: it’s true! When you have a “slow” or malfunctioning thyroid, your body won’t efficiently convert food into energy: instead, it turns that food into fat.

The thyroid also produces calcitonin, which we’ll talk about in the next section.


The parathyroids are four small glands that work together to release a single hormone called parathyroid hormone, which controls the level of calcium in your blood. The parathyroids work synergistically with calcitonin, a hormone produced in the thyroid, to regulate calcium levels in the bloodstream.

Adrenal Glands

The adrenal glands are two triangular-shaped glands found on the top of each kidney. They play an important role in our “fight or flight” response. Each gland produces two different types of hormones:

— Corticosteroids: These hormones regulate the salt and water balance in our body while also controlling metabolism, the immune system, stress, and sexual development and functionality.

— Catecholamines: One of the best-known catecholamines is epinephrine, which is also known as adrenaline. It controls our blood pressure and heart rate when the body experiences stress.


The pineal gland is found in the middle of the brain and secretes melatonin. Melatonin controls our sleep cycle. The body produces this chemical when it wants us to go to sleep.

How does the body know when you need to go to sleep? One of the primary factors is when it detects darkness through our eyes. When we stay up late staring at computer screens all night, it can inhibit our body’s production of melatonin, making it harder for us to fall asleep. This is why some people take a melatonin supplement to fall asleep: their pineal gland isn’t working properly.

Reproductive Glands

Both males and females have gonads, although they work in different ways.

In males, the gonads are the testes and they secrete hormones called androgens. One of the most important – and well-known androgen hormones is called testosterone.

In females, the gonads are the ovaries and they secrete female hormones like estrogen and progesterone.

Estrogen, progesterone, and testosterone all play important roles in the body’s reproductive cycles and sexual function.


The pancreas produces and secretes digestive enzymes. Your body uses these enzymes to break down food as it goes through the digestive system. Without enzymes, your body wouldn’t be able to extract the vitamins and nutrients it needs from the food you eat.

The pancreas does more than just produce enzymes: it also produces two hormones called insulin and glucagon. These hormones work synergistically to regulate blood sugar, which in turn helps your blood efficiently move vitamins and nutrients (i.e. fuel) throughout the body.

The Endocrine System Keeps your Hormones Balanced

When your endocrine system is working properly, it produces hormones which travel through the bloodstream and arrive at their targeted organs, producing their targeted effects.

The hormones arrive at their organs and latch onto special receptor cells. Each hormone has its own receptor cell. Once the hormone has latched onto the receptor cell, it can deliver its special instructions to the organ – like increasing our heart rate or telling our body to absorb more water into our bloodstream.

The endocrine system strives to keep hormones balanced throughout the body. After the thyroid has secreted the perfect amount of thyroid hormones, the pituitary gland will stop producing thyrotropin, which tells the thyroid to lower its production.

The endocrine system maintains this careful balancing act all the time in an effort to keep you healthy and happy.

What Are Endocrine Problems?

The endocrine system isn’t perfect. Sometimes, it develops problems which cause your hormones to become imbalanced.

Some of the most common endocrine problems include type 1 and type 2 diabetes, which is when the pancreas fails to produce enough insulin.

Some people also experience growth hormone problems when they’re growing up: their pituitary gland tells the bones to grow too big, causing conditions like gigantism, for example.

Two more common endocrine problems include hyperthyroidism and hypothyroidism. With hyperthyroidism, the thyroid releases too many thyroid hormones into the blood. With hypothyroidism, the thyroid doesn’t release enough thyroid hormones into the blood, which means your body can’t transform food into energy. Hypothyroidism typically leads to weight gain, immune system problems, and chronic fatigue.

Endocrine System Versus the Exocrine System

Don’t get the endocrine system confused with the exocrine system: the two systems are similar because they both secrete hormones. However, the exocrine system secretes its hormones using ducts, while the endocrine system secretes its hormones into the circulatory system.

Without the exocrine system, we wouldn’t be able to sweat or salivate. The exocrine system doesn’t release these hormones expecting to send them to the organs. Instead, it releases these hormones for other reasons: sweat cools us down when we’re overheating, for example, and saliva contains enzymes which digest the food we’re about to swallow.

The endocrine system is one of many systems which keep our body happy, healthy, and functional. Without hormones produced by the endocrine system, we wouldn’t be able to control blood sugar, stay hydrated, reproduce, or digest the foods we eat – just to name a few of its functions.


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