The pituitary gland is part of the endocrine system and produces several different hormones. In the human body, the pituitary gland is divided into three lobes: the anterior, intermediate, and posterior. Each lobe produces different pituitary gland hormones. Hormones produced in the anterior lobe include growth hormone and reproductive hormones. Pituitary gland hormones produced by the posterior lobe include oxytocin, while the intermediate lobe produces melanocyte-stimulating hormone.
The anterior lobe of the pituitary is responsible for the thyroid, reproductive glands, and adrenal glands. Pituitary gland hormones produced in the anterior lobe include thyrotropin, or thyroid stimulating hormone, which causes the thyroid to produce its own hormones. The anterior lobe is also responsible for growth hormone, which is in turn responsible for the development of bone and muscle tissue. Growth hormone also controls how the body burns fat or absorbs nutrients. Other pituitary gland hormones produced in the anterior lobe include corticotropin, which causes the adrenals to produce hormones such as cortisol.
Reproductive hormones are also produced in the anterior lobe. The hormone prolactin is released after women give birth to stimulate milk production in the mammary glands. Hormones that control the release of egg and sperm are also made in the anterior lobe. Follicle-stimulating hormone encourages production of eggs in the ovaries and regulates the release of estrogen and testosterone. Luteinizing hormone also stimulates the ovaries as well as the testes and is produced in the pituitary gland.
The middle or intermediate lobe of the pituitary gland produces melanocyte-stimulating hormone, which controls the pigmentation of a person's skin. The more of this hormone a person has, the darker his skin will be. Melanocyte-stimulating hormone can work with other hormones, such as estrogen, to cause skin darkening during certain periods of life. For example, some pregnant women may experience dark spots on their skin due to an increase in both hormones.
The posterior lobe is responsible for two pituitary gland hormones. It releases oxytocin, which causes the uterus to contract during childbirth. Oxytocin also prevents excessive bleeding after birth and encourages the flow of milk by causing the milk ducts in the breast to contract.
Anti-diuretic hormone (ADH), or vasopressin, also produced in the posterior lobe, helps to regulate the amount of water in the body. ADH is responsible for controlling the amount of water that the kidneys release into the bloodstream. The hormone is essential for keeping areas of the body hydrated.