Physiology

Question 1

What is the main axis involved in menstruation

Answer 1

Hypothalamic, ant. Pituitary gonadal axis

Question 2

Describe the first stages of the HPG axis

Answer 2

1. Activin causes hypothalamus to release GNRH
2. GnRH travels to ant. Pituitary
3. Ant. Pituitary releases LH and FSH
4. LH and FSH travel to ovaries and casue oestrogen and inhibin release

Question 3

What does inhibin do?

Answer 3

Inhibit activin, stopping release of GnRH, therefore reduces LH,FSH, OESTROGEN PROGESTERONE AND INHIBIN

Question 4

What does FSH do

Answer 4

Stimulate follicle production until a dominant one is found

Question 5

What does oestrogen do?

Answer 5

Regulate the cycle

Question 6

What does LH do>

Answer 6

Cause transformation of dominant follicle to corpus luteum which produces progesterone

Question 7

What does GnRh do?

Answer 7

Stimulate ant. Pituitary

Question 8

What hormone causes progesterone to be released

Answer 8

GnRH - LH - change of dominant follicle to corpus luteum - progesterone

Question 9

What does FSH do in the follicular phase?

Answer 9

1. Causes stimulation of growing follicles
2. Grows until main follicle is produced
3. That then produces lots of oestrogen
4. Oestrogen inhibits growth of other follicles

Question 10

What is the name of the dominant follicle in follicular phase?

Answer 10

Graafian follicle

Question 11

What does oestrogen do in the follicular phase?

Answer 11

1. Stop other follicles growing
2. Causes endometrial thickening
3. Thins cervical mucus
4. Inhibition of LH

Question 12

What’s the relationship between oestrogen and LH at day 12 follicular phase?

Answer 12

Oestrogen rises past a point which causes LH stimulation ad causes LH spike at day 12

Question 13

Describe the role of LH in changing Graafian follicle to ovum

Answer 13

LH spike causes Graafian follicle to become thinner, causing second oocyte release as it ruptures, secondary oocyte changes into optic and then matures into mature ovum that then is released and taken into fallopian tube by fimbriae

Question 14

What hormones act on the old Graafian follicle

Answer 14

LH and FSH to change Graafian follicle to corpus luteum

Question 15

What is the corpus luteum

Answer 15

Gland that starts to produce progesterone
Is degenerated when FSH and LH levels fall
Progesterone levels reduce then also

Question 16

What does increased progesterone do? (3)

Answer 16

1. Endometrium becomes ready to implant
2. Negative feedback causes decrease in LH AND FSH
3. Increases womens basal body temp

Question 17

What is the menstrual phase>

Answer 17

End of the luteal phase the corpus luteum degenerates
Loss of corpus luteum = less progesterone
Less progesterone - contraction of spiral arteries
Contraction of spiral arteries = loss of blood supply and necrotic tissue that sheds.

Question 18

What happens in the proliferative phase

Answer 18

Increasing levels of oestrogen due to increased LH AND FSH = repair of functional layer of endometrium

Question 19

What happens in secretory phase

Answer 19

Ovulations occured, progesterone from corpus luteum results in the secretion of substances from endometrial glands and make uterus more welcoming for embryo

Question 20

What is part of the uterine cycle

Answer 20

Proliferative, secretory and menstrual

Question 21

What is part of the menstrual cycle

Answer 21

Follicular and luteal

Question 22

What causes oestrogen to rise?

Answer 22

Follicular development and big release from first mature follicle

Question 23

What happens if that ovum is fertilised by sperm at the start of luteal phase/end of follicular phase

Answer 23

Ovum + sperm = happy egg
Happy egg release b-HCG
B-hCG allows corpus luteum to keep developing and releasing progesterone
Secretory phase is contact
Until 8 weeks where placenta then takes over corpus luteum job