Unit 2- Hormonal Control

Question 1

How long does the menstrual cycle last approximately?

Answer 1

28 days.

Question 2

What day does ovulation occur?

Answer 2

Usually day 14. Or about.

Question 3

What hormones are secreted from the pituitary gland which affect the menstrual cycle?

Answer 3

FSH, LH.

Question 4

What are the 2 phases in the menstrual cycle?

Answer 4

Follicular, luteal.

Question 5

Describe the follicular phase.

Answer 5

1. Cycle starts with menstruation ( breakdown of the lining of the uterus or endometrium) on day1.
2. Pituitary gland secretes FSH and LH. FSH stimulates the Development of a follicle and the production of oestrogen by the follicle.
3. Oestrogen stimulates the proliferation of the endometrium, preparing it for implantation. It also affects the consistency of cervical mucus.
4. Peak levels of oestrogen stimulate a surge in LH secretion. Surge in LH triggers ovulation.
5. High levels of oestrogen inhibit FSH production (negative feedback).

Question 6

Describe the luteal phase.

Answer 6

1. After ovulation, the follicle develops into the corpus luteam, which secretes progesterone.
2. Progesterone thickens the endometrium.
3. Progesterone induces(brings on) FSH and LH production.
4. The lack of LH leads to the corpus luteum degeneration. This leads to a decrease in progesterone which triggers menstration.
5. If fertilisation occurs progesterone levels remain high, as the corpus luteam does not degenerate.