An Introduction to the Endocrine System

The endocrine system controls the way your body functions. It produces hormones that travel to all parts of your body to maintain your tissues and organs. Here are a few of the areas governed by the endocrine system:

  • Reproduction
  • Responses to stress and injury
  • Growth and sexual development
  • Body energy levels
  • Internal balance of body systems
  • Bone and muscle strength

Your endocrine system produces, stores and releases hormones. When everything goes smoothly, your body functions properly.

The Glands of the Endocrine System

Your endocrine system is made of many glands and organs. They have different functions, and work together to keep you healthy. These are the glands of your endocrine system:

  • Adrenal glands - influence the way your body uses energy, they also release a hormone called adrenaline when you are under stress
  • Hypothalamus - part of your brain that controls hormone production by releasing different chemicals to the pituitary gland
  • Ovaries - produce estrogen and progesterone in women, and also release egg cells
  • Pancreas - releases the insulin your body needs to metabolize sugar; problems with the pancreas can lead to diabetes
  • Parathyroid - located behind the thyroid gland, they are essential for proper bone development
  • Pineal gland - connects the endocrine system with the nervous system; produces several important hormones, including melatonin, important to sleep/wake cycles and sexual development
  • Pituitary gland – likely the most important gland in your body, it is crucial to growth, mental development and reproduction; influences or controls the rest of your endocrine system
  • Testes - produce the hormone testosterone; in men, testosterone maintains sperm production and bone mass
  • Thymus - crucial to normal immune function in childhood; once a child reaches puberty, its tissue is replaced by fat
  • Thyroid gland – located in the front of your neck, it releases hormones that control your metabolism and govern the way your body uses energy

For a more in-depth look at all of the glands of the endocrine system, visit

Endocrine Organs

Several organs are vital to your endocrine system. They produce, store and excrete hormones to maintain the proper function of your body.

The placenta is the organ that provides the connection between a pregnant mother and the infant in her womb. It makes changes to a woman's body to better nourish her baby and prepare the mother for delivery.

Your skin, liver and kidneys work together to produce vitamin D. Vitamin D is produced when your skin is exposed to ultraviolet light. In the liver and kidneys, it becomes a chemical known as calcitriol, which maintains proper levels of calcium and phosphorus in your body.

Your stomach and small intestine secrete many hormones tied to eating and digestion. Disorders in the system can cause you to eat too little or too much food, and may lead to weight disorders. You can learn more here:

If you have any questions about your or your child’s endocrine system, talk to your doctor.


Bradley D. Anawalt, MD
University of Washington

Susan Kirk, MD
University of Virginia

Dorothy Shulman, MD
University of South Florida

Illustrator: Molly Feuer, 2013

Last Review: May 2013