What is the Pituitary Gland?

The pituitary gland is a pea sized gland located in a bony cavity just below the Hypothalamus, and above the sinus cavities and brain stem. It is an endocrine gland that creates, stores, and releases hormones directly into the blood. It receives it’s instructions from the hypothalamus and other glands, and is pared with the hypothalamus via the pituitary stalk. These glands working together have a dramatic effect on the entire endocrine system, hence they are referred to as “master glands”. There are two parts of the pituitary gland; the anterior and posterior lobes. Each will secrete their hormones through capillaries that drain into the hypophyseal vein branches.

The Anterior Pituitary lobe: Here lays a complex of cells that are responsible for creating and secreting hormones via releasing-hormones provided from the hypothalamus and negative feedback from other glands, that have profound effects on the endocrine system.

Growth hormone (somatotropin): Produced in the Somatotroph cells, this hormone encourages cell growth and reproduction. As well stimulates the liver to release Insulin-like growth factor 1.

Thyroid-stimulating hormone (thyrotropin):Produced in the Thyrotroph cells, this hormone stimulates the thyroid gland to synthesize and secrete thyroxine and triiodothyronine. It also stimulates iodine absorption by the thyroid.

Adrenocorticotropic hormone (corticotropin): Produced in the Corticotroph cells, this hormone stimulates the adrenocortical cells (located in the adrenal cortex) to produce and release androgen corticosteriod (glucocorticoid and mineralcorticoid).

Follicle-stimulating hormone: Produced in the Gonadotroph cells, this hormone stimulates the gonads of males and females. In males the testes are provoked to create androgen-binding proteins in the Sertoli cells, and stimulates spermatogenesis. In females it provokes the maturation of the ovarian follicles in the ovaries.

Luteinizing hormone: Produced in the gonadotroph cells, this hormone encourages reactions from both male and female gonads. In males it stimulates the creation of testosterone synthesis from leydig cells (interstitial cells) in the testes. In females it provokes the creation of corpus luteum and ovulation.

Prolactin: Produced in the lactotroph cells, this hormone stimulates the mamary glands to create and release milk. It also mediates sexual gratification.

The Posterior Pituitary lobe:This lobe is comprised mostly of neuronal or axonal projections from the Hypothalamus, through the pituitary stalk. Unlike the anterior lobe, the posterior does not synthesize hormones, but stores and releases hormones created in the hypothalamus.

Oxytocin: Produced in the hypothalamus, this hormone effects uterine contraction and lactation.

Vasopressin (antidiuretic hormone:Produced in the hypothalamus, this hormone instructs the Kidneys and arterioles to retain more water and in effect raises blood pressure by contracting arterioles. It will as well induce male aggression.