Question

Why do you call pituitary gland the master gland of the body? Write about it.

Answer 1

The pituitary gland or hypophysis is the smallest endocrine gland. It is a pea sized gland located just below the hypothalamus in the brain. It sits in the bony depression of sphenoid bone called sella turcica and is attached to the hypothalamus by a pituitary stalk or infundibulum.

Complete answer:
The pituitary gland consists of two distinct lobes, anterior and posterior. Each of these lobes have a different embryonic origin and function. The anterior pituitary is called adenohypophysis and is differentiated into three regions viz., pars distalis, pars intermedia and pars tuberalis. The posterior pituitary is called neurohypophysis or pars nervosa.

The pituitary is also known as the master gland. This is because its secretions regulate and control the activity of other endocrine glands like thyroid gland, ovary, testes, adrenal gland, pancreas etc. The anterior pituitary secretes most of the hormones which influence growth, sexual development, skin pigmentation, thyroid function, and adrenocortical functions.

Some important pituitary hormones that regulate the functioning of other endocrine gland are:

Thyroid stimulating hormone or Thyrotropin released from anterior pituitary controls the growth and activity of the thyroid gland and stimulates it to synthesise thyroxine and release it into blood.

Adrenocorticotropic hormone stimulates the cortex of the adrenal gland to produce glucocorticoids. Secretion of ACTH increases during emotional and physical stress.

Follicle Stimulating Hormone stimulates both male and female gametes. In females, FSH stimulates the ovary and its follicles to develop and mature. Whereas, in males FSH stimulates testes for development of seminiferous tubules and spermatogenesis.

Luteinizing Hormone or Interstitial Cell Stimulating Hormone is also a gonadotropin. In females, it is responsible for the final development of ovarian follicles and initiates the process of ovulation and formation of corpus luteum. In males, it stimulates the interstitial cells of testes to release male sex hormones or androgens.

Lactogenic or Prolactin or Luteotropic hormone stimulates the growth of mammary glands during pregnancy and initiates the secretion of milk after child birth. It also stimulates the corpus luteum to secrete progesterone hormone.

Melanocyte Stimulating Hormone or Intermedin is responsible for the synthesis of melanin pigment in melanophore or melanocyte cells.

Note: Pituitary secretes an important hormone called Growth hormone or somatotropin which acts directly on cells. A pituitary dysfunction may lead to a number of conditions like acromegaly, dwarfism, Cushing's syndrome, diabetes insipidus, hypogonadism, hypopituitarism and prolactinoma.