Human Physiology

Lesson 37 : Hypothalamus, Pitutary & Thyroid

Hypothalamus

Hormones secreted from hypothalamus are:

GnRH (Gonadotropin releasing hormone): It is a decapeptide causing release of gonadotropic hormones i.e. FSH & LH from anterior pituitary.

GHRF: (Growth hormone releasing factors):

There are two factors which contribute towards control of growth hormone secretion:

1. GHIF (Growth hormone inhibitory factor) - Tetradecapeptide and also found in gastro-intestinal tract. It inhibits growth hormone release from anterior pituitary.
2. GHRF (Growth hormone releasing factor) - It stimulates growth hormone release from anterior pituitary.

Sum total of GH secreted from hypophysis depends upon the balance of GHIF & GHRF.
CRF/CRH: (Corticotrophin Releasing Factor/Hormone): Secreted from anterior hypothalamus and affects secretion of ACTH from anterior pituitary.
PIF : (Prolactin Inhibitory Factor): It inhibits prolactin release from anterior pituitary.
PRF : (Prolactin Releasing Factor): It stimulates prolactin release from anterior pituitary.
The secretion of Prolactin from pituitary depends upon the net balance of these two however, but PIF is more important.
TRH : (Thyrotropin releasing hormone): A tripeptide, stimulates release of thyrotropin hormone (TSH) from anterior pituitary.