Name the hormones of the following endocrine glands and the function of each.
Pituitary, Thyroid, Adrenal, Thymus,Testis, Ovary
Pituitary, Thyroid, Adrenal, Thymus,Testis, Ovary
a. Pituitary- The pituitary gland is known as the master gland because it secretes growth hormone and many other hormones which regulate the secretion of many other endocrine glands in the body. Some of the hormones produced by pituitary are:
(i) Prolactin- Growth of mammary glands and formation of milk in them
(ii) TSH- Synthesis and release of thyroid hormones
(iii) Adrenocorticotrophic hormone (ACTH)- Stimulates synthesis and secretion of steroid hormones called glucocorticoids from the adrenal cortex
(iv) Vasopressin- Stimulates reabsorption of water from the distal tubules, and hence, prevents loss of water through urine (diuresis); therefore, also called anti-diuretic hormone (ADH)
b. Thyroid- Thyroid gland secretes the hormone, thyroxine (a derivative of amino acid tyrosine). Functions of thyroxine include:
(i) Control of BMR (Basal metabolism rate)
(ii) Control of working of kidney and urine formation
(iii) Regulation of physical, mental, and sexual growth
(iv) Regulation of growth of CNS and bones
(v) Regulation of carbohydrate and fat metabolism
c. Adrenal- Adrenal gland secretes 3 types of hormones- catecholamines, mineralocorticoids and glucocorticoids.
(i) Catecholamine (adrenaline and nor adrenaline)- They are also known as emergency hormones or hormones of fight or flight.
- Increases alertness, pupilary dilation, piloerection (raising of hair)
- Increases heart beat, respiration rate
- Stimulates the breakdown of glucose, lipids and proteins
(ii) Glucocorticoid: stimulates gluconeogenesis, lipolysis and proteolysis and inhibits uptake and utilisation of amino acids
(iii) Mineralocorticoid: Example − Aldosterone
- Acts on renal tubule and stimulates reabsorption of Na+ and water
- Stimulates excretion of K+
- Maintains electrolysis, osmotic pressure and blood pressure
- Androgenic steroids plays a role in the growth of axial, facial and pubic hair during puberty
d. Thymus- Thymus secretes peptide hormone called thymosins. Thymosins play an important role in the differentiation of T-lymphocytes (Cell Mediated Immunity) and promotes production of antibodies (Humoral Immunity). Thymus is degenerated in old people, hence, their immune response becomes weak.
e. Testes- Testis secrete hormones called androgens. Functions of androgens include:
- Development, maturation and functioning of the male accessory sex organs like vas deferens and seminal vesicles
- Stimulate muscular growth, growth of facial hair, low pitch voice, etc.
- Stimulatory role in spermatogenesis
- Act on the CNS and influence male sexual behaviour (libido)
- Anabolism of proteins and carbohydrates
f. Ovary- Ovary secretes the hormones oestrogen and progesterone.
Functions of oestrogen:
- Growth and functioning of the female secondary sex organs
- Development of growing follicles and mammary glands
- Regulates female secondary sex characters (Examples − high pitch voice)
Functions of progesterone:
- Acts on mammary glands and stimulates formation of alveoli-like structures storing milk
- Milk secretion
(i) Prolactin- Growth of mammary glands and formation of milk in them
(ii) TSH- Synthesis and release of thyroid hormones
(iii) Adrenocorticotrophic hormone (ACTH)- Stimulates synthesis and secretion of steroid hormones called glucocorticoids from the adrenal cortex
(iv) Vasopressin- Stimulates reabsorption of water from the distal tubules, and hence, prevents loss of water through urine (diuresis); therefore, also called anti-diuretic hormone (ADH)
b. Thyroid- Thyroid gland secretes the hormone, thyroxine (a derivative of amino acid tyrosine). Functions of thyroxine include:
(i) Control of BMR (Basal metabolism rate)
(ii) Control of working of kidney and urine formation
(iii) Regulation of physical, mental, and sexual growth
(iv) Regulation of growth of CNS and bones
(v) Regulation of carbohydrate and fat metabolism
c. Adrenal- Adrenal gland secretes 3 types of hormones- catecholamines, mineralocorticoids and glucocorticoids.
(i) Catecholamine (adrenaline and nor adrenaline)- They are also known as emergency hormones or hormones of fight or flight.
- Increases alertness, pupilary dilation, piloerection (raising of hair)
- Increases heart beat, respiration rate
- Stimulates the breakdown of glucose, lipids and proteins
(ii) Glucocorticoid: stimulates gluconeogenesis, lipolysis and proteolysis and inhibits uptake and utilisation of amino acids
(iii) Mineralocorticoid: Example − Aldosterone- Acts on renal tubule and stimulates reabsorption of Na+ and water
- Stimulates excretion of K+
- Maintains electrolysis, osmotic pressure and blood pressure
- Androgenic steroids plays a role in the growth of axial, facial and pubic hair during puberty
d. Thymus- Thymus secretes peptide hormone called thymosins. Thymosins play an important role in the differentiation of T-lymphocytes (Cell Mediated Immunity) and promotes production of antibodies (Humoral Immunity). Thymus is degenerated in old people, hence, their immune response becomes weak.
e. Testes- Testis secrete hormones called androgens. Functions of androgens include:
- Development, maturation and functioning of the male accessory sex organs like vas deferens and seminal vesicles
- Stimulate muscular growth, growth of facial hair, low pitch voice, etc.
- Stimulatory role in spermatogenesis
- Act on the CNS and influence male sexual behaviour (libido)
- Anabolism of proteins and carbohydrates
f. Ovary- Ovary secretes the hormones oestrogen and progesterone.
Functions of oestrogen:
- Growth and functioning of the female secondary sex organs
- Development of growing follicles and mammary glands
- Regulates female secondary sex characters (Examples − high pitch voice)
Functions of progesterone:
- Acts on mammary glands and stimulates formation of alveoli-like structures storing milk
- Milk secretion
