gonadal axis

Question 1

where is GnHR released from

Answer 1

hypothalamus

Question 2

how is GnHR released

Answer 2

in a pusaltile manner

Question 3

what does GnRH act on

Answer 3

the anterior pituitary

Question 4

what does the anterior pituitary produce

Answer 4

LH

FSH

Question 5

what causes FSH to be produced

Answer 5

Low frequency GnHR

Question 6

what causes LH to be produced

Answer 6

High frequency GnHR

Question 7

what does LH act on

Answer 7

testes

ovaries

Question 8

what does FSH act on

Answer 8

testes

ovaries

Question 9

what affect does FSH have on the testes

Answer 9

causes the testes to produce sperm (spermatogenesis)

Question 10

what does inhibin act on

Answer 10

FSH

Question 11

what affect does inhibin have on FSH

Answer 11

it inhibits its production to decrease FSH secretion

Question 12

what affect does LH have on the testes

Answer 12

causes the testes to produce testosterone

Question 13

how is GnHR released in males

Answer 13

at a constant rate

Question 14

what cassette release of testosterone

Answer 14

LH from the anterior pituitary

Question 15

what happens to the testosterone that is released

Answer 15

90% is taken up by sertoli cells the rest is free within the blood

Question 16

where are sertoli cells located

Answer 16

seminiferous tubules

Question 17

what does high levels of testosterone do

Answer 17

decreases GnRH causing a drop in LH

Question 18

what is the role of testosterone

Answer 18

maintains the testes-blood barrier

controls release of mature sperm from sertoli cells

Question 19

how long does spermatogenesis take

Answer 19

70 days

Question 20

what causes the release of GnHR, what are the receptors involved

Answer 20

FSH & LH

kisspeptide receptors

Question 21

how is LH released in females

Answer 21

released as a surge in response to high frequency GnHR

Question 22

what does LH cause in females

Answer 22

ovulation

formation of the corpus lutem which will produce and secrete progesterone

Question 23

what is the corpus lutem made of, when does it form

Answer 23

granulosa and theca cells which transform into luteal cells

forms after ovulation

Question 24

when does the LH surge occur

Answer 24

34-36hrs before ovulation

Question 25

when is FSH released in females

Answer 25

in response to low frequency GnHR

Question 26

what does FSH cause in females

Answer 26

growth of follicles

causes the ovary to secret oestrogen

Question 27

where is progesterone secreted from

Answer 27

corpus lutem

Question 28

what does progesterone do

Answer 28

pro-gestation (maintains pregnancy)
maintains endometrial thickness
relaxes myometrium
causes thick/infertile mucus

Question 29

what does do high levels of progesterone do

Answer 29

decreases GnHR causing a decreased LH

Question 30

when do progesterone levels peak

Answer 30

AFTER ovulation

Question 31

what produces oestrogen

Answer 31

ovaries, placenta an adrenals

Question 32

what does oestrogen do

Answer 32

thickens endometrium
reduces vaginal pH via lactic acid
decrease mucous viscosity
regulates LH surge

Question 33

how is the LH surge regulated

Answer 33

high levels of oestrogen causes increased GnHR which results in increased levels of LH

Question 34

when does oestrogen levels peak

Answer 34

BEFORE ovulation

Question 35

how long is a typical menstrual cycle

Answer 35

28-35 days

Question 36

what are the two phases of the menstrual cycle, when do they occur

Answer 36

before ovulation = follicular phase

after ovulation= luteal phase

Question 37

how long does the follicular phase last

Answer 37

typically 14 days +/- 7

very variable

Question 38

what is the follicular phase characterised by

Answer 38

follicular growth

Question 39

how long does the luteal phase last

Answer 39

14 days (very constant)

Question 40

what causes the formation of the corpus lutem

Answer 40

LH