Lecture 1 - Menstrual cycle

Question 1

What is the purpose of the menstrual cycle

Answer 1

generate oocyte
facilitate fertilisation
optimise endometrium for implantation
protect developing embryo

Question 2

What are the divisions of the menstrual cycle

Answer 2

Follicular - 1-14 (menstrual pahse and proliferative phase)

Luteal phase - 14-28 (secretory phase)

Question 3

Effects of the menstrual cycle

Answer 3

ovarian
endometrial
fallopian
cervical

Question 4

Describe the endocrine control of the menstrual cycle

Answer 4

Hypothalamus releases GnRh which stimulates AP to release FSH and LH which acts on ovary to produce oestrogen.

Oestrogen release is a negative feedback mechanism on Hypothalamus and pituitary

Question 5

What is GnRH and its structure

Answer 5

decapeptide
secreted by mid basal hypothalamic neurons
transported to pituitary hypophyseal portal blood system

Question 6

What affects secretion of GnRh

Answer 6

time zone
exercise
weight/loss/gain 
anxiety
time zone

Question 7

What are fsh and lh

Answer 7

glycoproteins

Question 8

Actions of FSH

Answer 8

Stimulates follicular activity

promotes estradiol production from granulosa cells

Question 9

LH actions

Answer 9

stimulates follice to release egg

promotes development of corpus luteum and production of progesterone

Question 10

When is negative feedback not applicable

Answer 10

near mid-cycle when high levels of E2 triggers release of LH (+VE feedback) - ovulation

Question 11

primordial follicles

Answer 11

degenerate as you grow older
450 follicles develop and produce an egg
no new produced

Question 12

Stages of follices

Answer 12

primordial - primary/preantral- secondary - preovulatory - ovulation

Question 13

at what day is the egg released

Answer 13

day 14

Question 14

What occurs during follicular development

Answer 14

proliferation of granulosa cells - antrum (fluid)
gap junctions and cytoplasmic processes allows communication and passage of nutrients
proliferation of thecal cells
theca interna - secrete circulating oestrogen - highly glandular and vascularised
theca externa - fibrous capsule

Question 15

What do the theca interna secrete

Answer 15

androgens and oestrogen

Question 16

what to androgens convert to

Answer 16

estradiol 17- beta in granulosa

Question 17

what happens in the luteal phase?

Answer 17

granulosa cells undergo luteinisation. forms the corpus luteum which releases progesterone and oestradiol 17 Beta

Question 18

What happens when there is no fertilisation

Answer 18

corpus luteum degnenrates and fibroses to become corpus albicans

Question 19

What happens in the proliferative phase?

Answer 19

secretion of estradiol (E2)
Endometrium thickens
increase in stroma and gland cells, blood vessels
endometrium 2-3 mm thick

Question 20

What happens during the secretory phase

Answer 20

progesterone dominant hormone
increased secretion of lipids and glycogen
increase in blood supply
optimal conditions for implantation

Question 21

What occurs during menstruation

Answer 21

vasodilation - vasospasms of BV
increase PGF2 alpha - blood supply cuts off
necrotic outer layers of endometrium separate from uterus
separate tissue and blood initiate uterine contractions

Question 22

What does the cervix produce

Answer 22

mucous from columnar glands
midcycle
inelastic during luteal phase - protect embryo, prevents microbial ingress
critical to pregnancy

Question 23

How does oral contraception work?

Answer 23

combined oral contraceptive
- contains estradiol and progestagen
steady levels of oestrogen and progesterone 
inhibit GnRh/FSH and LH
Thin endometrium
tenacious mucus