Endocrine Control of Ovarian and Menstrual Cycles

Question 1

What hormone is released by the hypothalamus and where does it act?

Answer 1

• Gonadotrophin releasing hormone (GnRH)

- Acts on pituitary gland

Question 2

What hormones does the pituitary gland release and where do they act?

Answer 2

• FSH + LH

- Act on ovary

Question 3

What hormones do the ovary produce and where do they act?

Answer 3

• Oestrogen + progesterone

- Act on the Uterus

Question 4

What effect does oestrogen have on days 12-14 of the cycle and why?

Answer 4

It shows a positive feedback loop on hypothalamus and pituitary to release more hormones in order to stimulate ovulation

Question 5

What are the phases of the ovarian cycle?

Answer 5

• Follicular
• Ovulation
• Luteal
• Mensturation

Question 6

What happens during the follicular phase of the ovarian cycle?

Answer 6

FSH causes follicle to mature and produce oestrogen (inhibiting development of other follicles)

Question 7

What happens during ovulatory phase of the ovarian cycle?

Answer 7

LH surge causes ovulation (follicle ruptures and releases a secondary oocyte)

Question 8

What happens during luteal phase of ovarian cycle?

Answer 8

Ruptured follicle forms a corpus luteum and secretes progesterone (and some oestrogen)

Question 9

What happens during menstrual phase of ovarian cycle?

Answer 9

When corpus luteum degenerates (forms a corpus albicans) a new ovarian cycle can begin