Anatomy of the Endocrine System

The endocrine system is made up of seven different glands (groups of cells) that make chemicals called hormones. Hormones are substances that act as "messengers" to control many body functions. The endocrine system makes more than 20 major hormones that help control:

  • Growth
  • Reproduction
  • Sexual development
  • Use and storage of energy
  • Response to physical stress or trauma
  • Levels of fluid, salt and sugar in the blood

The hypothalamus is located in the center of the brain. It makes hormones that increase or decrease the release of the hormones made in the pituitary gland. It also makes hormones that help to control water balance, sleep, temperature, appetite and blood pressure.

The pineal body is also located in the center of the brain. It produces the hormone melatonin, which is used by the body to keep the body's sleep cycle normal. 

The pituitary gland is located at the base of the brain and is about the size of a pea. It is the master gland in the endocrine system. It regulates the amounts of hormone made by the thyroid gland, adrenal gland, and testes or ovaries. It also makes the hormones prolactin and vasopressin, and growth hormone.

The thyroid gland and parathyroid glands are located in front of the neck, below the larynx (voice box). The thyroid plays an important role in the body's growth and development, as well as metabolism. Both the thyroid and parathyroid glands also play a role in controlling the level of calcium in the body.

The adrenal glands are located on top of each kidney. The adrenal glands make hormones that help the body deal with stress, and control sexual development. The hormones made by the adrenal gland also maintain other chemical levels in the body.  

The pancreas is located behind the stomach. It plays a role in digesting food, but it also makes hormones.  The pancreas makes insulin, which is important for blood sugar control.

A female's ovaries are located on both sides of the uterus, below the opening of the fallopian tubes (which extend from the uterus to the ovaries). In addition to containing the egg cells necessary for reproduction, the ovaries also produce the hormones estrogen and progesterone. These hormones regulate the menstrual cycle.

A male's testes are located in the scrotum, which hangs suspended outside his body. The testes produce testosterone and sperm.


Last Updated 06/2012