The Oestrous Cycle 0.0 / 5 ? BiologyHuman, animal and plant physiologyA2/A-levelAQA Created by: LZ95Created on: 09-04-14 18:23 What is the definition of the oestrous cycle? It is the regular pattern of changes that take place in the reproductive system of female mammals. 1 of 18 What is a menstrual cycle? A type of oestrous cycle where the lining of the uterus is shed along with some blood between each cycle. 2 of 18 What are the two hormones that are released from the pituitary gland? FSH and LH 3 of 18 What are the two hormones that are produced by the ovaries? Oestrogen and progesterone 4 of 18 What does FSH do? Stimulate development of follicles, stimulate the follicles in the ovaries to produce oestrogen. 5 of 18 What does LH do? Causes ovulation to occur, stimulates ovary to produce progesterone from the corpus luteum. 6 of 18 What does Oestrogen do? Rebuilds the lining of the uterus after menstruation, stimulates the pituitary gland to produce LH 7 of 18 What does progesterone do? Maintains lining of uterus (in readiness to receive the fertilised egg) and inhibits the production of FSH. 8 of 18 When does the menstrual cycle begin in humans? When the uterus lining is shed. 9 of 18 What is initially released into the blood by the pituitary gland? FSH 10 of 18 How is the uterus lining built back up? The growing follicles secrete small amounts of oestrogen which causes the uterus lining to build back up. It also inhibits the release of FSH + LH. 11 of 18 What happens at around day 10? Oestrogen concentration reaches a critical point where it starts to stimulate the release of FSH+LH. 12 of 18 What does the surge in FSH + LH production cause? Ovulation (a follicle releases its egg) 13 of 18 Which day does ovulation take place? Day 14 14 of 18 What does LH do after ovulation? Stimulates the empty follicle to develop into corpus luteum. 15 of 18 What does the corpus luteum secrete? Progesterone + small amounts of oestrogen 16 of 18 What happens if the egg is not fertilised? Corpus luteum degenerates so no more progesterone is produced. 17 of 18 What is the result of a decrease in progesterone? Lining of the uterus is no longer maintained so it breaks down, FSH production is no longer inhibited 18 of 18
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