Hormones of the pituitary gland

The pituitary gland controls the functions of all other glands in the endocrine system of our body.

It is situated inside the cranium on a small concave area over the sphenoid bone. It is divided into two parts anterior and posterior.

It is attached by a stalk like structure called infundibulum containing small blood vessels and nerve fibers to a part of the forebrain which is known as hypothalamus. This part of the forebrain regulates the function of pitutary gland.

It regulates the functions of other endocrine glands by secreting a specific hormone for every gland. The following hormones are secreted by the anterior pituitary.

• Growth hormone (GH): This directly acts on tissues to stimulate growth. Deficiency of this hormone causes short stature. Excess of this hormone causes gigantism in children and acromegaly in adults.

• Thyroid-stimulating hormone (TSH): This hormone acts on the Thyroid gland increasing the secretion of thyroid hormones. If the production of TSH is decreased due to any disease of the pituitary gland the function of thyroid gland also decreases.

• Adrenocorticotropic hormone (ACTH): Governs the function of the adrenal gland .

• Follicle-stimulating hormone (FSH): In females this hormone is responsible for the maturation of a ovarian follicle every month. In males it stimulates the production of sperms.

• Luteinizing hormone (LH): In females an increase in LH leads to rupture of the ovarian follicle and release of the ovum. In males it stimulates the cells of Leydig to secrete testosterone.

• Prolactin: This hormone is responsible for the production of breast milk after delivery. It is released in response to sucking of the nipple by the baby.

• Endorphins: These substances act as analgesics and produce a sense of well being.

The functions of other glands are controlled by a mechanism of feed back. Whenever the level of a particular hormone decreases or the demand for that hormone increases the pituitary gland secretes more of the hormone which acts on that gland responsible for production of the concerned hormone.

The posterior pituitary is actually an extension of the hypothalamus. It releases two hormones- antidiuretic hormone and oxytocin.

Antidiuretic hormone increases water re-absorption from the kidneys. Its deficiency causes a disease known as diabetes insipidus in which the kidneys are not able to concentrate urine and the person passes excess of urine and suffers from increased thirst.

Oxytocin plays an important role in child birth. It causes contraction of the uterine muscles and aids in delivery of the fetus. It also helps in ejection of breast milk so that the baby can easily suck the milk from the breast.

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