Publisher Summary Hormone secretions in the pituitary glands control the growth and activity of three other endocrine glands: the thyroid, adrenals, and gonads. This chapter describes the structure, physiology and functions of pituitary gland, and general aspects of the regulation of anterior pituitary function. It is a compound organ consisting of a neural or posterior lobe, a larger anterior portion, the adenohypophysis, and a small intermediate lobe. The hormones of pituitary are not limited in their activity to regulation of endocrine target glands; they also act directly on nonendocrine target tissues. There are six anterior pituitary hormones including thyrotropes, corticotropes, somatotropes, and lactotropes; all are proteins or glycoproteins. Secretion of anterior pituitary hormones is regulated by the central nervous system and hormones produced in peripheral target glands. Regulation of these hormones is subject to negative feedback inhibition by secretions of their target glands. In normal individuals, it is achieved through the interplay of stimulatory effects of releasing hormones and inhibitory effects of target gland hormones. The posterior pituitary gland secretes two hormones; oxytocin that increases uterine contractions during parturition and vasopressin that exerts contraction of vascular smooth muscle and thus raises blood pressure. The hormones of the posterior pituitary gland are synthesized and stored in nerve cells, and their secretion is controlled by neurotransmitters.