Menstrual cycle

Question 1

What is the purpose of the menstrual cycle?

Answer 1

production and release of ovum, thicken endometrium

Question 2

When does ovulation occur in the menstrual cycle?

Answer 2

Day 14

Question 3

Which organs are key in the HPG axis?

Answer 3

Hypothalamus, anterior pituitary gland and ovaries

Question 4

GnRH binds to what after being released from the hypothalamus?

Answer 4

APG

Question 5

What is released from the APG when GnRH is bound to it?

Answer 5

LH (luteinising) and FSH

Question 6

LH and FSH trigger what?

Answer 6

oestrogen and inhibin release from the ovaries

Question 7

What does inhibin do?

Answer 7

Cause the inhibition of activin; activin is initially responsible for stimulating GnRH production

Question 8

What does FSH do?

Answer 8

Stimulates follicles, causes the most sensitive follicle to become the dominant Graafian follicle

Question 9

What does the LH do to the Graafian follicle?

Answer 9

Stimulates it into the corpus luteum

Question 10

What is released by the corpus luteum?

Answer 10

Progesterone

Question 11

Which hormone helps regulate the menstrual cycle?

Answer 11

Oestrogen

Question 12

Which hormone causes inhibition of activin and stimulates GnRH production?

Answer 12

Inhibin

Question 13

What stimulates the development of ovarian follicles?

Answer 13

FSH

Question 14

What triggers the graafian follicle to become the corpus luteum?

Answer 14

LH

Question 15

What hormone triggers the endometrium to thicken and become more receptive to implantation?

Answer 15

Progesterone

Question 16

What are the two phases of the menstrual cycle called?

Answer 16

Follicular and Luteal

Question 17

What is the start of the follicular phase?

Answer 17

Rise in levels of FSH causing the stimulation of a few ovarian follicles

Question 18

The first follicle that becomes mature releases what?

Answer 18

Oestrogen

Question 19

What does oestrogen inhibit?

Answer 19

Other competing follicles from growing

Question 20

The graafian follicle is what?

Answer 20

The single follicle that reaches full maturity

Question 21

Where does the oocyte develop?

Answer 21

Within the Graafian follicle

Question 22

What does increased oestrogen trigger?

Answer 22

Endometrial thickening; thinning of cervical mucus; inhibition of LH from APG

Question 23

What happens around day 12?

Answer 23

Oestrogen levels pass a threshold and

Question 24

What causes the membrane of the Graafian follicle to become thinner?

Answer 24

LH

Question 25

What happens 24-48 hours after the Graafian follicle experiences the LH surge

Answer 25

It ruptures and releases a secondary oocyte which matures into an ootid and then a mature ovum

Question 26

Where is the mature ovum released into?

Answer 26

The peritoneal space and taken into the fallopian tube via the fimbriae i.e. finger like projections

Question 27

What marks the end of the follicular phase? and around what day is this?

Answer 27

Mature ovum enters the fallopian tube. Day 14

Question 28

What marks the start of the luteal phase?

Answer 28

Once ovulation has occurred, the Graafian follicle develops into the corpus luteum

Question 29

What hormones are released in the Luteal phase

Answer 29

Progesterone, via the Corpus Luteum

Question 30

What happens as a result of increased progesterone? (3 things)

Answer 30

Increased bod temp, endometrium becomes receptive, negative feedback resulting in decreased LH and FSH = degrading corpus luteum

Question 31

What happens as a result of the degeneration of the corpus luteum

Answer 31

Loss of progesterone production

Question 32

What happens when progesterone levels are lost?

Answer 32

Menstruation and the cycle starts again

Question 33

What layers is the endometrium compose of?

Answer 33

2: functional and basal layer (basal layer is not shed)

Question 34

What are the phases of the uterine cycle?

Answer 34

3: PSM, proliferative, secretory and menstrual

Question 35

Key features of the proliferation phase?

Answer 35

increased oestrogen levels due to FSH stimulating its production, which repairs the functional endometrial layer (from recent menstruation)

Question 36

Key features of the secretory phase

Answer 36

increased progesterone, occurs once ovulation has started, makes embryo a welcoming environment for implantation

Question 37

Key features of the menstrual phase

Answer 37

Corpus luteum degenerates, results in decreased progesterone production, spiral arteries in the functional endometrium contract, ischaemic and necrotic environment = shed