Feedback Mechanisms

Question 1

Describe the oestrus cycle.

Answer 1

• The lining of the uterus is shed and blood is released
• The pituitary gland released FSH which stimulates the follicles mature and release oestrogen
• This creates a low oestrogen level in the blood which prevents FSH and LH from being released so the uterus thickens
• The follicles grow, stimulating the production of FSH and LH, due to high oestrogen levels, which increase until they reach a peak
• The egg is released
• The empty follicle (corpus luteum) releases progesterone which inhibits the production of FSH and LH so the lining of the uterus thickens
• The corpus luteum degenerates if the egg is not fertilised so the cycle begins again