Hormonal Control of Male Reproductive Functions

1
Hormonal Control of Male Reproductive Functions

• Hormones are secreted by
• Hypothalamus
• Anterior pituitary gland
• Testes
• Functions
• Development of sperm cells
• Development of secondary sex characteristics

2
Hypothalamic and Pituitary Hormones

• Hypothalamus secretes gonadotropin-releasing
  hormone (GnRH) to anterior pituitary gland
• In response, anterior pituitary gland secretes
  gonadotropins
• Luteinizing hormone (LH)
• Follicle-stimulating hormone (FSH), aka
  interstitial cell-stimulating hormone (ICSH)

3
Hypothalamic and Pituitary Hormones, continued..

• FSH (ICSH) promotes development of ___________.
• Testicular interstitial cells secrete male sex
  hormones.
• LH stimulates supporting cells of seminiferous
  tubules to respond to testosterone.

4
Hypothalamic and Pituitary Hormones, continued..

• FSH testosterone supporting cells stimulate
  spermatogenic cells to give rise to
  ______________.
• Supporting cells secrete inhibin, a hormone which
  inhibits the anterior pituitary gland, preventing
  secretion of FSH.

5
Male Sex Hormones

• Called Androgens (???)
• Where are they produced?
• Most in testicular interstitial cells, but small
  amounts in adrenal cortex
• What is the main male sex hormone?
• Testosterone production begins before birth,
  continues a few weeks after, and then ceases
  until puberty.

6
Actions of Testosterone

• Stimulates enlargement of testes and male
  accessory organs
• Stimulates development of male secondary sex
  characteristics
• Increased growth of body hair
• Enlargement of the larynx and thickening of the
  vocal cords
• Thickening of the skin
• Muscle growth, widening of shoulders, narrowing
  of waist
• Thickening and strengthening of bones

7
Actions of Testosterone, continued..

• Increases rate of cellular metabolism
• Increases rate of RBC production

8
Regulation of Male Sex Hormones

• More testosterone more developed secondary sex
  characteristics
• Increased levels of testosterone inhibit the
  hypothalamus.
• What effects would inhibition of the hypothalamus
  have?