Biology
Endocrine Glands and Hormones
* Endocrine glands lack ducts and are hence, called ductless glands. Their secretions are called hormones.
* Hormone is a chemical produced by endocrine glands and released into the blood and transported to a distantly located target organ
* The endocrine glands and hormone producing diffused tissues/cells located in different parts of our body constitute the endocrine system. Pituitary, pineal, thyroid, adrenal, pancreas, parathyroid, thymus and gonads (testis in males and ovary in females) are the organized endocrine bodies in our body.
* Some other organs, e.g., gastrointestinal tract, liver, kidney, heart also produce hormones.
Hypothalamus
* It is the part of the forebrain and it regulates a wide spectrum of body functions.
It contains several groups of neurosecretory cells called nuclei which produce hormones.
These hormones regulate the synthesis and secretion of pituitary hormones
* A hypothalamic hormone called Gonadotrophin releasing hormone (GnRH) stimulates the pituitary synthesis and release of gonadotrophins.
* A hypothalamic hormone called somatostatin inhibits the release of growth hormone from the pituitary.
Pituitary Gland
* The pituitary gland is located in a bony cavity called sella tursica and is attached to hypothalamus by a stalk.
* It is divided anatomically into an adenohypophysis and a neurohypophysis.
Prolactin (PRL)
* Prolactin regulates the growth of the mammary glands and formation of milk in them.
Thyroid Stimulating Hormone (TSH)
* TSH stimulates the synthesis and secretion of thyroid hormones from the thyroid gland.
Adrenocorticotrophic Hormone (ACTH)
* ACTH stimulates the synthesis and secretion of steroid hormones called glucocorticoids from the adrenal cortex.
Luteinizing Hormone (LH) and Follicle Stimulating Hormone (FSH)
* LH and FSH stimulate gonadal activity and hence are called gonadotrophins.
LH stimulates the synthesis and secretion of hormones called androgens from testis in males.
In males, FSH and androgens regulate spermatogenesis.
LH induces ovulation of fully mature follicles (graafian follicles) and maintains the corpus luteum, formed from the remnants of the graafian follicles after ovulation in females.
FSH stimulates growth and development of the ovarian follicles in females