1. Menstrual Cycle

Question 1

What is the purpose of the menstrual cycle?

Answer 1

1. Generate an oocyte
2. Facilitate fertilisation
3. Optimise endometrium for implantation
4. Protect developing embryo

Question 2

What is a menarche?

Answer 2

First bleed

menopause is last bleed

Question 3

What is the term for the shredding of the previous cycle’s endometrium?

Answer 3

Menstruation

Question 4

The hypothalamus releases GnRH in ——

Complete the sentence.

Answer 4

pulses

Question 5

Where is gonadotrophin released from?

Answer 5

Anterior pituitary gland

gonadotrophin = FSH / LH

Question 6

How often is GnRH secreted?

Answer 6

Hourly pulse

Question 7

Chaotic or missing menstrual bleeding can occur if GnRH secretion is disturbed.
Which of these is GnRH secretion not affected by?
bereavement
anxiety
hunger
time zone
day/night duty
exercise
stress
weight loss/gain

Answer 7

hunger

stress

Question 8

What is the role of FSH?

Answer 8

Stimulates follicular activity, causing the egg to mature.

Also stimulates estradiol production in follicle (tells anterior pituitary to ↓ FSH production and ↑ LH production).

Question 9

What is the role of LH?

Answer 9

Triggers the release of an egg from the dominant follicle and development of the corpus luteum which produces progesterone.

Question 10

FSH and LH are glycoproteins with the same β chain, but different α chains.
True or False?

Answer 10

FALSE

same α, different β

Question 11

High levels of E2 (estradiol) leads to a surge in LH release.
True or False?

Answer 11

FALSE

this is true at midcycle, but normally GnRH, LH and FSH production is inhibited by ↑ E2

Question 12

Outline the life cycle of the primordial follicle from start to finish?

Answer 12

1. Primordial follicle
2. Preantral follicle
3. Early antral follicle
   4, Later antral follicle

Ovulation

5. Oocyte / Courpus luteum

Question 13

Approximately how many follicles from the original 2,000,000 primordial follicles in the foetus develop and produce an egg?

Answer 13

450

Question 14

In terms of hormones, how is ovulation brought about?

Answer 14

1. ↑ oestrogen levels due to almost mature follicle stimulates the release of GnRH (hypothalamus) + LH (anterior pituitary).
2. GnRH stimulates the release of FSH (anterior pituitary) and more LH
3. Surge of LH causes ovulation

Question 15

What is the precursor to all sex steroids?

Answer 15

Cholesterol

Question 16

What effect does estradiol (E2) have on the endometrium?

Answer 16

Endometrium thickens (2-3mm at ovulation).
↑ stromal cells
↑ glands
↑ blood vessels

Question 17

Progesterone is the dominant hormone in the secretory phase of the menstrual cycle.
What effect does it have?

Answer 17

Makes endometrium more stable for the implantation of a fertilised egg.
4-6mm thick.
↑ blood supply, ↑ nutrients

Question 18

What function does the remaining corpus luteum have?

Answer 18

Secretes progesterone

Question 19

What happens to the corpus luteum if implantation doesn’t occur?

Answer 19

Corpus luteum degenerates, progesterone secretion stops and menstruation shedding begins.

Question 20

The fertilised egg divides as it moves through the fallopian tube and reaches the uterus at the blastocyte stage.
True or False?

Answer 20

TRUE

Question 21

Mucus produced by the cervix is stringy and runny in the luteal phase.
True or False?

Answer 21

FALSE
This consistency at midcycle.
Tenacious + inelastic at luteal phase to prevent bacteria entering (mucus plug).

Question 22

On what days are you most fertile?

Answer 22

days 12 - 14

Question 23

What do oral contraceptives contain?

Answer 23

Estradiol + progestogen (synthetic progesterone)

Question 24

Oral contraceptives inhibit GnRH/FSH/LH.

What effect does this have?

Answer 24

1. Prevents ovulation
2. Thin endometrium
3. Tenacious mucus