The Endocrine System and Glands of the Human Body

Medically Reviewed by Poonam Sachdev on August 28, 2023
6 min read

The endocrine system is a network of glands in your body that make the hormones that help cells talk to each other. They’re responsible for almost every cell, organ, and function in your body.

photo of endocrine system anatomy

If your endocrine system isn't healthy, you might have problems developing during puberty, getting pregnant, or managing stress. You also might gain weight easily, have weak bones, or lack energy because too much sugar stays in your blood instead of moving into your cells where it's needed for energy.


A gland is an organ that makes and puts out hormones that do a specific job in your body. Endocrine and exocrine glands release the substances they make into your bloodstream.


What does your endocrine system do? Its glands create and release hormones that control almost all processes in your body. They coordinate your metabolism, growth, and development, and control your emotions, mood, sexual function, and even sleep. Your endocrine system:

  • Makes hormones that control your moods, growth and development, metabolism, organs, and reproduction
  • Controls how your hormones are released
  • Sends those hormones into your bloodstream so they can travel to other body parts

Many glands make up the endocrine system. The hypothalamus, pituitary gland, and pineal gland are in your brain. The thyroid and parathyroid glands are in your neck. The thymus is between your lungs, the adrenals are on top of your kidneys, and the pancreas is behind your stomach. Your ovaries (if you're a woman) or testes (if you're a man) are in your pelvic region.

Endocrine glands

  • Hypothalamus. This organ connects your endocrine system with your nervous system. Its main job is to tell your pituitary gland to start or stop making hormones.
  • Pituitary gland. This is your endocrine system’s master gland. It uses information it gets from your brain to tell other glands in your body what to do. It makes many important hormones, including growth hormone; prolactin, which helps breastfeeding moms make milk; antidiuretic hormone (ADH or vasopressin), which controls blood pressure and helps control body water balance through its effect on the kidneys; adrenocorticotropic hormone (ACTH), which stimulates the adrenal gland to make certain hormones; thyroid-stimulating hormone (TSH), which stimulates the production and secretion of thyroid hormones; oxytocin, which helps in milk ejection during breastfeeding; and luteinizing hormone, which manages estrogen in women and testosterone in men.
  • Pineal gland. It makes a chemical called melatonin that helps your body get ready to go to sleep.
  • Thyroid gland. This gland makes thyroid hormone, which controls your growth and metabolism. If this gland doesn't make enough (a condition called hypothyroidism), everything happens more slowly. Your heart rate might slow down. You could get constipated. And you might gain weight. If it makes too much (hyperthyroidism), everything speeds up. Your heart might race. You could have diarrhea. And you might lose weight without trying. The thyroid gland also produces the hormone calcitonin, which may contribute to bone strength by helping calcium get incorporated into bone.
  • Parathyroid. This is a set of four small glands behind your thyroid. They play a role in bone health. The glands control your levels of calcium and phosphorus.
  • Thymus. This gland makes white blood cells called T lymphocytes that fight infection and are crucial as a child's immune system develops. The thymus starts to shrink after puberty.
  • Adrenals. Best known for making the "fight or flight" hormone adrenaline (also called epinephrine), these two glands also make hormones called corticosteroids. They affect your metabolism heart rate, oxygen intake, blood flow, and sexual function, among other things.

Endocrine organs

  • Pancreas. This organ is part of your digestive and endocrine systems. It makes digestive enzymes that break down food. It also makes the hormones insulin and glucagon. These ensure you have the right amount of sugar in your bloodstream and your cells.
  • If you don't make insulin, which is the case for people with type 1 diabetes, your blood sugar levels can get dangerously high. In type 2 diabetes, the pancreas usually makes some insulin but not enough.
  • Ovaries. In women, these organs make estrogen and progesterone. These hormones help develop breasts at puberty, regulate the menstrual cycle, and support a pregnancy.
  • Testes. In men, the testes make testosterone. It helps them grow facial and body hair at puberty. It also tells the penis to grow larger and plays a role in making sperm.
  • Acromegaly. Sometimes the pituitary gland makes too much growth hormone and your bones get bigger. It usually affects your hands, feet, and face. It usually starts in middle age.
  • Addison's disease. Also called adrenal insufficiency, this happens when your body makes too little cortisol. That's the hormone that controls stress. 
  • Amenorrhea. This menstrual condition happens when you have no periods for more than three monthly menstrual cycles. 
  • Cushing's disease. In this, your body makes too much cortisol. You could gain weight, get stretch marks, bruise easily at first, then get weakened muscles and bones and possibly develop a hump on your upper back.
  • Hyperthyroidism. This is when your thyroid gland makes more hormones than your body needs. You might hear it called overactive thyroid. It makes your system run fast, and you might feel nervous, lose weight, and have a rapid heartbeat or trouble sleeping. Studies show it's more common in women. 
  • Hypogonadism. This is when your testes or ovaries produce little or no amount of hormones
  • Hypothyroidism. When your body doesn’t make enough thyroid hormone, your system slows down. You might feel tired, gain weight, have a slow heartbeat, and get joint and muscle pains.
  • Hypopituitarism. Sometimes your pituitary gland doesn’t make enough of certain hormones and your adrenal and thyroid glands can’t work right.
  • Multiple endocrine neoplasia. This is a group of disorders that affect your endocrine system. It causes tumors on at least two endocrine glands or in other organs and tissues.
  • Osteoporosis. This is an endocrine disorder where hormones you need for healthy bone growth are compromised. It happens when your body's creation of new bone doesn't keep up with your loss of old bone. 
  • Polycystic ovary syndrome. An imbalance of reproductive hormones can cause your ovaries to either not make an egg or not release it during ovulation. This can throw off your periods, cause acne, and make hair to grow on your face or chin.
  • Precocious puberty. When glands that control reproduction don’t work properly, some kids start puberty too early – around age 8 in girls and 9 in boys.
  • Premature ovarian failure. Also called ovarian hypofunction, this refers to the reduced function of your ovaries and reduced production of hormones in the female reproductive system.

Endocrine disorder symptoms

As you get older, it's natural to notice some changes related to your endocrine system. Some common signs include:

  • Your metabolism tends to slow down. So you might gain weight even though you haven't changed how you eat or exercise. 
  • You can have a higher risk of heart disease, osteoporosis, and type 2 diabetes as you age.

No matter how old you are, stress, infections, and being around certain chemicals can also mess with parts of your endocrine system. Your genes or lifestyle habits can increase your chances of an endocrine disorder like hypothyroidism, diabetes, or osteoporosis.

  • Your endocrine system is a network of glands in your body that make the hormones that help your cells talk to each other. 
  • Your endocrine system is responsible for almost every cell, organ, and function in your body.
  • If your endocrine system doesn't work correctly, you can have various health conditions, including serious medical problems. 
  • You're likely to have more health issues related to your endocrine system as you age. 


How can I keep my endocrine system healthy?

Keep your endocrine system healthy the same way you keep the rest of your body healthy: Get regular exercise, eat healthy foods,  and see your doctor for regular checkups.

How does my endocrine system work with my nervous system?

Your endocrine system sends chemical messengers that carry directions to your key organs, by way of your nervous system, for your growth, reproduction, metabolism, and other processes.

When should I call my doctor?

See your doctor if you have any of these symptoms of diabetes or other medical conditions:

  • Frequent urge to pee
  • Extreme thirst
  • Lasting nausea or stomach pain
  • Sudden and unexplained weight loss or weight gain
  • Severe exhaustion or weakness
  • Excess sweating
  • Sudden episodes of rapid heartbeat or high blood pressure
  • Developmental or growth delays