The Pituitary gland is a pea-sized endocrine (hormone-producing) gland weighing about 0.5 g situated at the bottom of the skull sandwiched between the optic nerves, in humans. The pituitary gland secretes hormones. Hormones are chemicals that travel through the blood stream. The pituitary gland is every now and then called the "master" gland of the endocrine system, as it controls the functions of the other endocrine glands, such as the temperature, thyroid activity, growth during early days of birth, urine production, testosterone production in males and ovulation and estrogen production in females. The pituitary is functionally connected to the hypothalamus, a part of the brain that has a number of small nuclei with a variety of functions. The pituitary fossa, in which the pituitary gland rests, is located in the sphenoid bone, an unpaired bone situated at the base of the brain. The pituitary gland secretes nine hormones that regulate homeostasis, the property of a system, either open or closed, that regulates its internal environment and tends to maintain a stable, constant condition.
The pituitary gland is vital as it conveys messages from the brain by means of a gland called the hypothalamus and make use these messages to manufacture hormones that affect numerous parts of the body and activating all the other hormone-producing glands to generate their own hormones. This is the reason why it is called the “Master gland”.
The pituitary gland has 3 parts:
I. The Anterior pituitary (or adenohypophysis): The Anterior (or front) pituitary produces hormones that affect the breasts, adrenals, thyroid, ovaries and testes, in addition to several other hormones. The anterior pituitary receives its signals from the ‘parvocellular neurons’ in the brain. The anterior pituitary synthesizes and secretes the vital endocrine hormones, such as:
These hormones are released from the anterior pituitary under the influence of the hypothalamus. Hypothalamic hormones are secreted to the anterior lobe through an unique way of a special capillary system, called the hypothalamic-hypophysial portal system.
II. Intermediate lobe: There exist an intermediate lobe in several animals, but is basic in humans. For example, it is assumed to control physiological color change in fishes. 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 vaguely credited to the anterior pituitary. MSH is secreted to control skin pigmentation.
III. The posterior pituitary (or neurohypophysis): The main glands affected by the posterior (or rear) pituitary are the kidneys. The posterior pituitary receives its signals from ‘magnocellular neurons’ in the brain. The posterior pituitary gland stores and releases hormones, such as:
Both anterior and posterior glands are functionally linked to the hypothalamus by the pituitary stalk. It is from the hypothalamus that hypothalamic tropic factors are discharged to move down the pituitary stalk to the pituitary gland where they rouse the discharge of pituitary hormones. Both of the lobes are controlled by the hypothalamus.
Hormones secreted from the pituitary gland aid controls the body processes, such as:
A specialized cell transmitting nerve impulses called the ‘neurons’ transmit messages concerning the production of hormones between the pituitary gland and the hypothalamus. Together they are situated at the base of the brain, snuggled in a rounded part of bone, vigilantly secluded. They are linked by a bunch of neurons called the ‘infundibulum’. In concert, they work to regulate all the hormones that circulate in the bloodstream, controlling things like growth and hair pigmentation. Hormones are the long-distance messengers that can notify cells when to become active or stay inactive. The pituitary gland controls the thyroid, adrenal glands, ovaries and testes, in spite of its tiny size.
The major cause of pituitary disorders is ‘pituitary gland tumors’. The pituitary gland is made of a number of cell types. At times, these cells grow too much or produce small growths. These growths are called pituitary tumors, and they are fairly common in adults. These are not brain tumors and are not a form of cancer. Actually, cancerous tumors of this kind are extremely unusual. Pituitary tumors, on the other hand, can obstruct with the normal formation and release of hormones.
There are two types of tumors exist:
The various concerns caused by pituitary tumors fall into three major groups: