Chemical Coordination and integration — BIOLOGY STD 11 Science — Question

Hypothalamus is a super master endocrine gland as it secretes hormones that regulate the synthesis and secretion of pituitary gland which is a master gland. The hypothalamus is connected to the anterior lobe of pituitary gland by hypophysial portal veins, however, it is connected to the posterior lobe of pituitary gland mainly by axons of nuerosecretory cells. The hormones produced by hypothalamus are of two types, the releasing hormones (which stimulate the secretion of pituitary hormones) and the inhibiting hormones (which inhibit secretions of pituitary hormones). The hormones secreted by hypothalamus are summarized below:

1. Adrenocorticotropic Releasing Hormone (ARH) or Corticotrophin Releasing Hormone – It stimulates the anterior lobe of the pituitary gland to secrete its adrenocorticotropic hormone (ACTH).
2. Thyrotrophic Releasing Hormone (TRH)- It stimulates the anterior lobe of the pituitary gland to secrete its thyroid stimulating hormone (TSH). or thyrotrophic.
3. Growth Hormone-Releasing Hormone (GHRH)- It stimulates the anterior lobe of the pituitary gland to release its growth hormone (GH) or somatotrophin.
4. Growth Hormone-Inhibitory Hormone (GHIH)- This hormone is also called somatostatin (SS). It inhibits the secretion of growth hormone from the anterior lobe of the pituitary gland.
5. Gonadotropin Releasing Hormone (GnRH)- It stimulates the anterior lobe of the pituitary gland to secrete two gonadotropic hormones : Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH)).
6. Prolactin Releasing hormone (PRH)- It stimulates the anterior lobe of the pituitary gland to secrete its prolactin hormone.
7. Prolactin Inhibitory Hormone (PIH)- It inhibits the secretion of prolactin from the anterior lobe of pituitary gland.
8. MSH Releasing Hormone (MSHRH)- It stimulates the intermediate lobe of the pituitary gland to secrete its melanocyte stimulating hormone (MSH).
9. MSH Inhibitory Hormone (MSHIH)- It inhibits the secretion of melanocytes stimulating hormone from the intermediate lobe of the pituitary gland.