Menstrual Cycle

Question 1

What are the two phases of the menstrual cycle?

Answer 1

Phase 1 = Follicular phase

Phase 2 = Luteal Phase

Question 2

What does the hypothalamus produce which leads to the anterior pituitary to release FSH and LH?

Answer 2

Gonadotrophin releasing hormone (GnRH)

Question 3

Each follicle is made up by a primary oocyte surrounded by which two hormone producing cells of the ovary?

Answer 3

Theca cells

Granulosa cells

Question 4

During first 10 days: theca cells grow receptors to what hormone?

This stimulates the production of what?

Answer 4

LH

Produce androstenedione in response to LH binding

Question 5

During first 10 days: granulosa cells grow receptors to what hormone?

This stimulates the production of what?

Answer 5

FSH

Produce aromatase which converts androstenedione to estradiol (an oestrogen)

Question 6

During days 10-14: granulosa cells develop LH receptors, leading to production of what?

Answer 6

Oestrogen

Question 7

What effect does oestrogen have on the anterior pituitary?

Answer 7

Negative feedback = less FSH and LH

Question 8

What effect does less FSH have on developing follicles?

Answer 8

Most die off

Follicle with most FSH receptors = dominant / Graafian follicle

Question 9

What is the effect of the rising oestrogen levels on anterior pituitary?

Answer 9

Now becomes positive feedback - makes pituitary more sensitive to GnRH - surge of FSH and LH production

Question 10

What does the surge of FSH and LH lead to?

Answer 10

Rupture of ovarian follicle leading to release of oocyte = ovulation

Question 11

What day is ovulation?

Answer 11

Day 14

Question 12

What are the two phases of the uterus?

Answer 12

1) Menstrual phase
- old endometrial lining shed
- 5 days
2) Proliferative phase
- Rising oestrogen = thickening of endometrium, growth of endometrial glands and emergence of spiral arteries, thickening of cervical mucus

Question 13

Which days are the most optimum days for fertilisation in a 28 day cycle?

Answer 13

Day 11 and 15

Question 14

What happens to the remnant of the ovarian follicle?

Answer 14

It becomes the corpus luteum

Question 15

What is the corpus luteum made up of?

Answer 15

Luteinised theca and granulosa cells (exposed to high LH levels before ovulation)

Question 16

Luteinised granulosa cells lead to the production of what?

Answer 16

Progesterone and inhibin

Question 17

Which hormone is dominant during the luteal phase?

Answer 17

Progesterone

Question 18

Progesterone and inhibin do what?

Answer 18

-ve feedback on pituitary, deceasing LH and FSH production, decreasing oestrogen production

Question 19

Rising progesterone does what to endometrium?

Answer 19

Thickens it - entering it into secretory phase

After day 15 optimal window for fertilisation to occur closes, thickening cervical mucus less hospitable for sperm

Question 20

What does the corpus luteum degenerate into?

Answer 20

Corpus albicans

= doesn’t make hormones - decreasing levels of oestrogen and progesterone
- spiral arteries collapse and functional layer sloughs off