Major endocrine system

Endocrine System Overview

The endocrine system is a network of glands and organs located throughout the body. It’s similar to the nervous system in that it plays a vital role in controlling and regulating many of the body’s functions.

However, while the nervous system uses nerve impulses and neurotransmitters for communication, the endocrine system uses chemical messengers called hormones.

Keep reading to discover more about the endocrine system, what it does, and the hormones it produces.

The endocrine system is responsible for regulating a range of bodily functions through the release of hormones.

Hormones are secreted by the glands of the endocrine system, traveling through the bloodstream to various organs and tissues in the body. The hormones then tell these organs and tissues what to do or how to function.

Some examples of bodily functions that are controlled by the endocrine system include:

  • metabolism
  • growth and development
  • sexual function and reproduction
  • heart rate
  • blood pressure
  • appetite
  • sleeping and waking cycles
  • body temperature

What is a gland?

A gland is an organ that creates and releases substances that the body needs to function. There are two types of glands:

  • endocrine glands, which release hormones directly into the bloodstream
  • exocrine glands, like lymph nodes and sweat glands, which are not part of the endocrine system

The glands of the endocrine system are where hormones are produced, stored, and released. Each gland produces one or more hormones, which go on to target specific organs and tissues in the body.

The glands of the endocrine system include the:

  • Hypothalamus. While some people don’t consider it a gland, the hypothalamus produces multiple hormones that control the pituitary gland. It’s also involved in regulating many functions, including sleep-wake cycles, body temperature, and appetite. It can also regulate the function of other endocrine glands.
  • Pituitary. The pituitary gland is located below the hypothalamus. The hormones it produces affect growth and reproduction. They can also control the function of other endocrine glands.
  • Pineal. This gland is found in the middle of your brain. It’s important for your sleep-wake cycles.
  • Thyroid. The thyroid gland is located in the front part of your neck. It’s very important for metabolism.
  • Parathyroid. Also located in the front of your neck, the parathyroid gland is important for maintaining control of calcium levels in your bones and blood.
  • Thymus. Located in the upper torso, the thymus is active until puberty and produces hormones that are important for the development of a type of white blood cell called a T cell.
  • Adrenal. One adrenal gland can be found on top of each kidney. These glands produce hormones that are important for regulating functions such as blood pressure, heart rate, and stress response.
  • Pancreas. The pancreas is located in your abdomen behind your stomach. Its endocrine function involves controlling blood sugar levels.

Some endocrine glands also have non-endocrine functions. For example, the ovaries and testes produce hormones, but they also have the non-endocrine function of producing eggs and sperm, respectively.

Hormones are the chemicals the endocrine system uses to send messages to organs and tissue throughout the body. Once released into the bloodstream, hormones travel to their target organ or tissue, which has receptors that recognize and react to the hormone.

Below are some examples of hormones that are produced by the endocrine system.

Hormone Secreting gland(s) Function
adrenaline adrenal increases blood pressure, heart rate, and metabolism in reaction to stress
aldosterone adrenal controls the body’s salt and water balance
cortisol adrenal plays a role in stress response
dehydroepiandrosterone sulfate (DHEA-S) adrenal aids in production of body odor and growth of body hair during puberty
estrogen ovary works to regulate the menstrual cycle, maintain pregnancy, and develop female sex characteristics; aids in sperm production
follicle-stimulating hormone (FSH) pituitary controls the production of eggs and sperm
glucagon pancreas helps increase levels of blood glucose (blood sugar)
insulin pancreas helps reduce your blood glucose levels
luteinizing hormone (LH) pituitary controls estrogen and testosterone production as well as ovulation
melatonin pineal controls sleep-wake cycles
oxytocin pituitary helps with lactation, childbirth, and mother-child bonding
parathyroid hormone parathyroid controls calcium levels in bones and blood
progesterone ovary helps prepare the body for pregnancy when an egg is fertilized
prolactin pituitary promotes breast-milk production
testosterone ovary, teste, adrenal contributes to sex drive and body density in males and females as well as development of male sex characteristics
thyroid hormone thyroid helps control several body functions, including the rate of metabolism and energy levels

Explore the interactive 3-D diagram below to learn more about the endocrine system.

Sometimes, hormone levels can be too high or too low. When this happens, it can have a number of effects on your health. The signs and symptoms depend on the hormone that’s out of balance.

Here’s a look at some conditions that can affect the endocrine system and alter your hormone levels.


Hyperthyroidism happens when your thyroid gland makes more thyroid hormone than necessary. This can be caused by a range of things, including autoimmune conditions.

Some common symptoms of hyperthyroidism include:

  • fatigue
  • nervousness
  • weight loss
  • diarrhea
  • issues tolerating heat
  • fast heart rate
  • trouble sleeping

Treatment depends on how severe the condition is, as well as its underlying cause. Options include medications, radioiodine therapy, or surgery.

Graves‘ disease is an autoimmune disorder and a common form of hyperthyroidism. In people with Graves‘ disease, the immune system attacks the thyroid, which causes it to produce more thyroid hormone than usual.


Hypothyroidism occurs when your thyroid doesn’t produce enough thyroid hormone. Similar to hyperthyroidism, it has many potential causes.

Some common symptoms of hypothyroidism include:

  • fatigue
  • weight gain
  • constipation
  • issues tolerating the cold
  • dry skin and hair
  • slow heart rate
  • irregular periods
  • fertility issues

Treatment for hypothyroidism involves supplementing your thyroid hormone with medication.

Cushing syndrome

Cushing syndrome happens due to high levels of the hormone cortisol.

Common symptoms of Cushing syndrome include:

  • weight gain
  • fatty deposits in the face, midsection, or shoulders
  • stretch marks, particularly on the arms, thighs, and abdomen
  • slow healing of cuts, scrapes, and insect bites
  • thin skin that bruises easily
  • irregular periods
  • decreased sex drive and fertility in males

Treatment depends on the cause of the condition and can include medications, radiation therapy, or surgery.

Addison’s disease

Addison’s disease happens when your adrenal glands don’t produce enough cortisol or aldosterone. Some symptoms of Addison’s disease include:

  • fatigue
  • weight loss
  • abdominal pain
  • low blood sugar
  • nausea or vomiting
  • diarrhea
  • irritability
  • a craving for salt or salty foods
  • irregular periods

Treatment for Addison’s disease involves taking medications that help replace the hormones your body isn’t producing enough of.


Diabetes refers to a condition in which your blood sugar levels aren’t regulated within a certain range.

People with diabetes have too much glucose in their blood (high blood sugar). There are two types of diabetes: type 1 diabetes and type 2 diabetes.

Some common symptoms of diabetes include:

Treatment for diabetes can include blood sugar monitoring, insulin therapy, and medications. Lifestyle changes, such as getting regular exercise and eating a balanced diet, can also help.

Polycystic ovary syndrome (PCOS)

This common condition is caused by unbalanced reproductive hormones in people with ovaries, which can create issues in the ovaries. Living with PCOS can mean that an egg may not be released every month, or may not develop as it should when it is released.

Some of the common symptoms of PCOS are:

  • irregular periods
  • fertility issues
  • cysts that form on the ovaries
  • acne
  • hirsutism, which is an unusual amount of hair growth on the face or chin
  • thinning hair
  • weight gain
  • skin tags

Treatment for PCOS focuses on easing the symptoms. Treatments include medications, like birth control and metformin, and lifestyle changes, such as focusing on nutrition and trying to reach a moderate weight if your doctor has recommended it.


A common condition, especially in older males and occasionally in females, hypogonadism is caused by a lowered production of the sex hormone testosterone. This can lead to lowered libido, as well as a variety of other symptoms, such as:

Treatment for hypogonadism focuses on improved testosterone levels. Testosterone replacement therapy and lifestyle changes (such as working toward a moderate weight if your doctor has recommended it) are two popular methods.


Osteoporosis is an abnormal loss of bone mass and changes in bone tissue. It can be caused by a variety of issues, but two common causes are lowered estrogen levels in people with ovaries and lowered testosterone levels in people with testicles. These lowered hormone levels can be caused by age, as well as other diseases.

Osteoporosis doesn‘t always cause obvious symptoms. But some of the more common symptoms are bone fractures and injuries related to minor falls, lifting, and even coughing.

Treatment for osteoporosis focuses on slowing or stopping bone loss. Proper nutrition, exercise, and medications are three of the most common treatments.


This rare disease is caused when the body makes too much growth hormone, which is mainly produced in the pituitary gland. Mostly diagnosed in middle-aged adults, it can cause organs, bones, cartilage, organs, and certain tissues to grow in size.

  • swollen nose
  • swollen ears
  • swollen hands and feet
  • joint aches
  • a deeper voice than usual
  • an increase in sweating and body odor

Treatment for acromegaly includes medications, radiation therapy, and surgery.

The endocrine system is a complex collection of glands and organs that helps regulate various bodily functions. This is accomplished through the release of hormones, or chemical messengers, produced by the endocrine system.

Last medically reviewed on March 12, 2022