Menstruation

Question 1

What is variation in cycle length

Answer 1

Vary greatly

e.g. 20-45 days in adolescence

Question 2

What % of cycles are 28 days

Answer 2

Only 12%

Question 3

When are cycles likely to be irregular and anovulatory

Answer 3

Soon after menarche and before menopause

Question 4

What are the 3 stages on menstruation

Answer 4

Menstrual phase
Proliferative phase
Secretory phase

Question 5

Menstrual phase

Answer 5

Day 1-5

Question 6

Proliferative phase

Answer 6

Day 6-14

Question 7

Secretory phase

Answer 7

Day 15-28

Question 8

Menstrual phase- what happens

Answer 8

Withdrawal of steroid support of oestrogen and progesterone, so endometrium collapses

Question 9

Menstrual phase- shedding

Answer 9

Endometrium shed together with blood from ruptured arteries (spinal arteries contract to reduce bleeding)

Question 10

Menstrual phase average blood loss

Answer 10

Usually between 20-80ml

Median 28ml

Question 11

Menstrual phase- around 10-15% of women lose more than

Answer 11

80ml

Question 12

Menstrual phase- What % of women who lose more than 80ml become anaemic

Answer 12

60%

Question 13

Menstrual phase- 70% of blood loss occurs within the first

Answer 13

48 hours

Question 14

What is the menstrual flow

Answer 14

Detached endometrial tissue and blood passing through the vagina

Question 15

Proliferative phase- what happens

Answer 15

Oestrogen from the mature follicle stimulates thickening of endometrium
Glands + spiral arteries form

Question 16

Proliferative phase- what does oestrogen stimulate

Answer 16

Thickening of endometrium

Synthesis of progesterone receptors on endometrial cells

Question 17

Secretory phase- what happens

Answer 17

Progesterone from corpus luteum act on endometrium

Question 18

Secretory phase- what does progesterone stimulate

Answer 18

Enlargement of glands which begin secreting mucus and glycogen in preparation for implantation of the fertilised oocyte

Question 19

Secretory phase- what happens if fertilisation doesn’t occur

Answer 19

Corpus luteum degenerates
Progesterone levels fall
Endometrium degenerates
Cycle starts again with first day of menstrual flow