reproduction physiology and biochemistry

Question 1

what are the 2 gonadotrophic hormones that the pituitary gland secretes?

Answer 1

FSH
LH

Question 2

what is the purpose of FSH?

Answer 2

Male: causes the testes to produce sperm (spermatogenesis)

Female: causes the growth of ovarian follicles (oogenesis) and it causes the ovary to secrete oestrogen

Question 3

what is the purpose of LH?

Answer 3

Male: causes the testes to secrete testosterone

Female: causes ovulation and it causes progesterone production by the Corpus Luteum

Question 4

what type of hormone is GnRH

Answer 4

neuropeptide hormone

Question 5

which hormone is stimulated in high frequency GnRH pulses?

Answer 5

LH

Question 6

which hormone is stimulated in low frequency GnRH pulses?

Answer 6

FSH

Question 7

an increase in which hormone reduces frequency of GnRH pulses?

Answer 7

progesterone

Question 8

Do GnRH neurons have receptors for oestrogen and progesterone?

Answer 8

No, so therefore indirect regulation

Question 9

what are the phases of the menstrual cycle?

Answer 9

follicular phase
then ovulation
then luteal phase

Question 10

what actually regulated GnRH pulsitility?

Answer 10

kisspeptide receptors

Question 11

what stimulates ovarian follicle growth (and therefore a rise in oestrogen levels) ?

Answer 11

FSH

Question 12

what does the rise in oestrogen levels lead to?

Answer 12

temporarily lower FSH
THEN once a threshold is reached there is an increase in FSH and a surge in LH

Question 13

what does the LH surge lead to?

Answer 13

progesterone increase

Question 14

what is folliculogenesis?

Answer 14

with rising oestrogen levels (associated with follicle growth), FSH levels initially decrease (negative feedback at HPA-axis) so only the follicle able to cope with this fall in FSH (likely to be the one with the most FSH receptors and highest vascularity) can survive this decrease. Others are lost

Question 15

when does the corpus luteum form?

Answer 15

under the influence of LH

Question 16

how does the corpus luteum form?

Answer 16

granulosa and theca cells transform to luteal cells

Question 17

what hormone is increased in the formation of the corpus luteum?

Answer 17

progesterone

Question 18

how does the increase in progesterone in the formation of the corpus luteum occur?

Answer 18

LH stimulates angiogenesis (ensures efficient delivery of cholesterol (substrate for progesterone synthesis))
LH stimulates enzymes involved in conversion of cholesterol to progesterone

Question 19

what is the main functions of oestrogen?

Answer 19

Increase the thickness of the vaginal wall
Regulate the LH surge
Reduce vaginal pH through increase in lactic acid production
Decrease viscosity of cervical mucus to facilitate sperm penetration

Question 20

what is the function of progesterone?

Answer 20

Maintains the thickness of the endometrium

Responsible for infertile thick mucus (prevent sperm transport and help prevent infection)

Relaxes the myometrium (smooth muscle). Functional progesterone withdrawal thought to regulate parturition (birth)

Question 21

what the optimal route for sperm to pass through?

Answer 21

through PG (primary grooves) and SG (secondary grooves), avoiding thick mucus and immune cells

Question 22

which cells take up most of the testosterone?

Answer 22

Sertoli cells (about 90%)

Question 23

what is the role of testosterone during spermatogenesis?

Answer 23

Maintains the integrity of the blood-testes barrier
Release of mature spermatozoa from Sertoli cells by influencing peritubular myoid cells