#Pituitary_gland
The pituitary gland is known as the 'master gland' and is also described as the 'conductor of the endocrine orchestra'. The pituitary gland is an oval shaped reddish-grey body of about 10 mm in diameter, located at the base of the brain, below the hypothalamus in a depression called hypophyseal fossa. The pituitary gland is composed of two parts: adenohypophysis and neurohypophysis. Adenohypophysis is composed of three divisions: pars distalis, pars tuberalis, and pars intermedia. Neurohypophysis consists of two divisions: pars nervosa and infundibulum or pituitary stalk.
#Hormones of pituitary gland
The hormones secreted by the pituitary gland are called 'tropins'. These hormones control and regulate the production of hormones produced by other glands, including testes and ovaries.
#Hormones #of_adenohypophysis
The adenohypophysis secretes the following seven hormones:
- Growth hormone (GH) or somatotropic hormone (STH) or somatotropin
- Adrenocorticotropic hormone (ACTH) or adrenocorticotropin
- Thyroid stimulating hormone (TSH) or thyrotropin
- Prolactin (PRL) or lactogenic hormone or luteotropic hormone (LTH)
- Follicle stimulating hormone (FSH)
- Luteinizing hormone (LH) or interstitial cell-stimulating hormone (ICSH)
- Melanocyte stimulating hormone (MSH) or intermedin
#Growth_Hormone (GH)
Growth hormone promotes the growth of bones, cartilage, and muscles. GH also stimulates the absorption of calcium from the intestine, helps in the conversion of glycogen to glucose, increases the breakdown of triglycerides in adipocytes, and increases protein synthesis. Hyposecretion of GH leads to 'dwarfism' in children and 'Simmond's disease' in adults. Hypersecretion of the hormone leads to 'gigantism' in children and 'acromegaly' in adults.
#Adrenocorticotropic_Hormone (ACTH)
ACTH stimulates the adrenal glands to produce glucocorticoids such as cortisol, and adrenal androgens. ACTH promotes increased urinary excretion of phosphorus, potassium, and nitrogen. It also promotes retention of sodium and chloride in blood.
Thyroid Stimulating Hormone (TSH)
TSH stimulates the secretion of thyroxin by thyroid gland. It regulates the rate of iodine intake by the thyroid gland. Hyposecretion of TSH leads to hypothyroidism, marked by decreased functional activity of thyroxin. Hypersecretion of TSH leads to hyperthyroidism, characterized by excessive thyroid function.
Prolactin (PL)
LH stimulates breast development and milk secretion from mammary glands in women. It is responsible for activating and maintaining corpus luteum and continued secretion of progesterone. Hyposecretion causes poor milk production in nursing women and hypersecretion leads to cessation of menses.
Follicle Stimulating Hormone (FSH)
FSH stimulates the growth and maturation of graafian (ovarian) follicle and secretion of estrogen in females. It promotes spermatogenesis in males. Hyposecretion of FSH leads to hypogonadism.
Luteinizing Hormone (LH)
In females, LH stimulates the graafian follicles to burst leading to ovulation. Ovulation results in the formation of corpus luteum, which subsequently secretes progesterone. In males, LH stimulates the release of androgens (like testosterone) into the blood. Hyposecretion of LH leads to delayed puberty, hypogonadism, and reproductive abnormalities.
Melanocyte Stimulating Hormone (MSH)
MSH is responsible for the distribution of melanin pigment granules produced by melanocytes, onto the skin epidermis. Higher amount of melanin causes darkening of the skin.
Hormones of neurohypophysis
The extract of the neurohypophysis is called 'pituitrin' and this contains two hormones:
- Vasopressin or antidiuretic hormone (ADH)
- Oxytocin
Vasopressin or Antidiuretic Hormone (ADH)
ADH is synthesized in the hypothalamus of the brain and is later transported to the neurohypophysis for secretion. It elevates blood pressure by its action on arterioles throughout the body. It stimulates re
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