Gynaecology Physiology

Question 1

What is the effect of oestrogen on the hypothalamus and pituitary gland?

Answer 1

Negative feedback at moderate levels

Positive feedback at high levels

Question 2

What is the effect of progesterone on the hypothalamus and pituitary gland?

Answer 2

Negative feedback

Question 3

What hormones are seen in the menstrual cycle and where are they released from?

Answer 3

GnRH - Hypothalamus
FSH - Anterior Pituitary
LH - Anterior Pituitary
Oestrogen - Ovaries
Progesterone - Corpus luteum

Question 4

What stimulates ovulation?

Answer 4

LH surge due to +ve feedback from Oestrogen

Question 5

What are the phases of the menstrual cycle?

Answer 5

Follicular phase 0-14
Luteal phase 14-28
Menses 28-0

Question 6

What happens to the uterine wall throughout the cycle?

Answer 6

Build up in follicular and luteal phases until being shedded in menses

Question 7

What causes the menses?

Answer 7

Progesterone drop

Ovum not fertilised so corpus luteum –> corpus albicans and no longer produces progesterone

Question 8

Describe what happens in the menstrual cycle

long card

Answer 8

Low levels of sex steroids mean little -ve feedback –> FSH and LH rise

Oestrogen levels rise and negatively feeds back on FSH

Oestrogen levels high enough to +ve feedback –> LH surge

Ovulation

Follicle remains luteinised and secretes oestrogen and progesterone. -ve feedback on axis due to progesterone

Corpus luteum produce oestrogen, progesterone and inhibin to maintain fertilisation conditions

After 14 days corpus luteum regress - decrease in sex steroids - axis reset

Question 9

Why is FSH selectively inhibited?

Answer 9

Inhibin acts selectively on FSH to inhibit it

Question 10

Why does oestrogen still rise if FSH levels drop?

Answer 10

Oestrogen production becomes independent of FSH due to granulosa cells expressing LH receptors