Question

1. Explain how the release of FSH is regulated by negative feedback. Be sure to include all the hormones that are involved and how they affect the release of FSH.

Answer 1

Answer

• FSH (follicle stimulating hormone) is a gonadotropic hormone released by anterior pituitary gland.
• FSH release is stimulated by GnRH (gonadotropin releasing hormone) from the hypothalamus.
• FSH release is regulated by a negative feedback mechanism.
  
  
• In females, FSH stimulates growth of ovarian follicles and release of hormone estrogen.
• When estrogen levels increase in the blood, it triggers a negative feedback to inhibit hypothalamic release of GnRH.
• Declining levels of GnRH inturn prevent anterior pituitary gland from releasing FSH.
• Granulosa cells of ovarian follicles also release a hormone called inhibin. It acts on anterior pituitary gland and prevents the release of FSH.
  
  
• In males, FSH acts on sertoli cells of testes and promote spermatogenesis.
• Increase in spermatogenesis and increased levels of androgens (testosterone) in the blood stimulates the release of inhibin hormone from the sertoli cells.
• Inhibin supresses the release of FSH from anterior pituitary.
• High testosterone levels in blood also triggers negative feedback on hypothalamus preventing the release of GnRH and inturn FSH.