Hormones and the pituitary gland

The anterior lobe makes growth hormone, which controls metabolism, above all the making of proteins, and so controls the growth of the body. Too little of it in childhood leads to dwarfism, too much in childhood to gigantism, and too much in an adult to acromegaly, in which the bones of the hands, feet and face grow larger. People differ in height for many reasons, so only a doctor can say whether a hormone is involved. The anterior lobe also makes tropic hormones that act on other glands: TSH on the thyroid, ACTH on the cortex of the adrenal gland, and FSH and LH on the gonads. In a female FSH stimulates the growth of the ovarian follicles, and LH stimulates the forming of the corpus luteum. In a male FSH acts on the seminiferous tubules, where sperms are made, and LH acts on the interstitial cells of the testis. Prolactin stimulates the mammary glands to make milk. The two hormones of the posterior lobe are made by nerve cells in the hypothalamus, travel down the stalk and are stored in nerve endings until they are needed, when they pass into the blood. ADH makes the kidney tubules take back more water, so less urine is passed, and it also raises blood pressure. Oxytocin makes the uterus contract in labour and the breasts release milk during breast feeding; in hospital, doctors can use it to strengthen contractions.