2.2 Hormonal control of Reproduction Flashcards
Pituitary Gland
Stimulated to release FSH and LH in females and ICSH in males by the releaser hormone produced in hypothalamus. This triggers the onset of puberty.
FSH in males
Promotes sperm production in seminferous tubules
ICSH in males
Stimulates the production of testosterone in the interstitial cells
Action of Testosterone
Also stimulates sperm production and activates prostate gland and seminal vesicles
Negative feedback of testosterone
High levels of testosterone will inhibit FSH and ICSH production in the pituitary gland. This will lower testosterone levels.
As testosterone levels lower, it will stop inhibiting the pituitary gland and FSH and ICSH will be produced again. This will increase testosterone levels.
The Menstrual Cycle
Takes approximately 28 days with the first day of menstruation regarded as day one of the cycle.
Stages of the Menstrual Cycle
• FSH stimulates the development of the follicle and the production of oestrogen
by the follicle in the follicular phase.
• Oestrogen stimulates proliferation of the endometrium and affects the
consistency of cervical mucus making it more easily penetrated by sperm. Peak
levels of oestrogen stimulate a surge in the secretion of LH.
• The surge in LH triggers ovulation and stimulates the development of the follicle
into the corpus luteum in the luteal phase. The corpus luteum produces
progesterone.
• Progesterone promotes further development and vascularisation of the
endometrium preparing it for implantation if fertilisation occurs.
High levels of Progesterone and Oestrogen
In the luteal phase inhibit the pituitary gland and reduce levels of FSH and LH.
Lack of LH
Leads to the degeneration of the corpus luteum which leads to a drop in progesterone levels which causes menstruation.
If Fertilisation does occur…
The corpus luteum does not degenerate and progesterone (and oestrogen) levels remain high.
