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Pituitary gland

The pituitary gland, or hypophysis, is an endocrine gland about the size of a pea. It is a protrusion off the bottom of the hypothalamus at the base of the brain, and rests in a small, bony cavity (sella turcica) covered by a dural fold (diaphragma sellae). The pituitary fossa, in which the pituitary gland sits, is situated in the sphenoid bone in the middle cranial fossa at the base of the brain.

The pituitary gland secretes hormones regulating homeostasis, including tropic hormones that stimulate other endocrine glands. It is functionally connected to the hypothalamus by the median eminence.

Sections

Located at the base of the brain, the pituitary is functionally linked to the hypothalamus. It is composed of two lobes: the adenohypophysis and neurohypophysis. The adenohypophysis, also referred to as the anterior pituitary is divided into anatomical regions known as the pars tuberalis, pars intermedia, and pars distalis. The neurohypophysis, also referred to as the posterior pituitary. The pituitary is functionally linked to the hypothalamus by the pituitary stalk, whereby hypothalamic releasing factors are released and in turn stimulate the release of pituitary hormones.

Anterior pituitary (Adenohypophysis)

The anterior pituitary synthesizes and secretes important endocrine hormones, such as ACTH, TSH, PRL, GH, endorphins, FSH, and LH. These hormones are released from the anterior pituitary under the influence of hypothalamus. Hypothalamic hormones are secreted to the anterior lobe by way of a special capillary system, called the hypothalamic-hypophyseal portal system.it is developed from dorsalwall of pharynx(stomodial part) i.e called as 'ruthke's pouch'. they all transport by special nerve cells present in the hypothalamus.such nerve cells are located in various parts of hypothalamus & send their nerve fibre into median eminence & tubar cinerium(b/w ant. &post. lobe).

Posterior pituitary (Neurohypophysis)

The hormones secreted by the posterior pituitary are

Oxytocin, where the majority is released from the paraventricular nucleus in the hypothalamus
Antidiuretic hormone (ADH, also known as vasopressin and AVP, arginine vasopressin), the majority of which is released from the supraoptic nucleus in the hypothalamus

Oxytocin is one of the few hormones to create a positive feedback loop. For example, uterine contractions stimulate the release of oxytocin from the posterior pituitary, which in turn increases uterine contractions. This positive feedback loop continues until the baby is born.

Intermediate lobe

There is also an intermediate lobe in many animals. For instance in fish it is believed to control physiological colour change. In adult humans it is just a thin layer of cells between the anterior and posterior pituitary. The intermediate lobe produces melanocyte-stimulating hormone (MSH), although this function is often (imprecisely) attributed to the anterior pituitary.

Functions

The pituitary hormones help control some of the following body processes:

Growth
Blood pressure
Some aspects of pregnancy and childbirth including stimulation of uterine contractions during childbirth
Breast milk production
Sex organ functions in both women and men
Thyroid gland function
The conversion of food into energy (metabolism)
Water and osmolarity regulation in the body

Pathology

Disorders involving the pituitary gland include:

Condition	Direction	Hormone
Acromegaly	overproduction	growth hormone
Growth hormone deficiency	underproduction	growth hormone
Syndrome of inappropriate antidiuretic hormone	overproduction	vasopressin
Diabetes insipidus	underproduction	vasopressin
Sheehan syndrome	underproduction	any pituitary hormone
Pituitary adenoma	overproduction	any pituitary hormone
Hypopituitarism	underproduction	any pituitary hormone