The endocrine system

The endocrine system is a network of glands that secrete hormones to regulate metabolism, growth, sexual function, reproduction, and other processes. Hormones are vital to our health, but also play a role in common diseases.

The major glands of the endocrine system include the hypothalamus, pituitary gland, ovaries and testes, in addition to the thyroid gland, adrenal glands, and pancreas.

A small region within the brain that controls vital functions including eating and drinking, sexual function, heart rate, and blood pressure. The hypothalamus releases hormones into blood vessels that connect to the pituitary gland.

Pituitary gland
Located below the hypothalamus at the base of the brain, the pituitary gland is divided into two parts: the anterior and the posterior pituitary. The pituitary gland produces many important hormones, including gonadotropins, which regulate the production of sex hormones by the ovaries and testes.

Ovaries & testes
The ovaries and testes serve two major functions: the production of eggs and sperm and the production of sex hormones. The ovaries produce estrogen and progesterone. The testes produce testosterone.

The hypothalamus, pituitary gland, ovaries, and testes produce and release hormones that control processes throughout the body. These glands respond to one another and are particularly important for sexual reproduction.

Kisspeptin & GnRH
Kisspeptin is a key regulator of reproduction, including the onset of puberty. Kisspeptin stimulates the release of gonadotropin-releasing hormone (GnRH). GnRH stimulates the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary gland.

LH stimulates the production of estrogen and progesterone by the ovaries and testosterone by the testes. FSH stimulates the development of ovarian follicles, which contain eggs, and sperm production. LH and FSH are gonadotropins.

Estrogen & testosterone
Estrogen and testosterone are necessary for the development and function of reproductive organs and secondary sex characteristics like breast development and facial hair. Estrogen is an essential hormone in the menstrual cycle, and testosterone is required for sperm production.

How do hormones support our health?

Hormones act as chemical messengers throughout the body. Hormones play a vital role in many important processes and are required for good health.


Key chemical processes depend on hormones. For example, thyroid hormones stimulate the breakdown of carbohydrates, proteins, and lipids, to generate energy required by the body.


The process of increasing in size is fundamental to the body. Hormones like growth hormone (GH) stimulate bone and organ growth.

Sexual Function

Important components of sexual function include development and function of reproductive organs and sexual desire. Estrogen and testosterone play a central role in these processes.


The fertilization of the human egg by sperm is a central event in reproduction. Many hormones are required for this event, including LH, FSH, estrogen, progesterone, and testosterone.

Learn more about menstruation and infertility.

Hormones play a role in common diseases

The endocrine system has evolved to regulate hormones and balance their effects. Diseases like insulin-dependent diabetes and hyperthyroidism result from imbalances in the endocrine system. Hormones also drive common diseases like uterine fibroids, endometriosis, and prostate cancer.