gonads

Question 1

hypothalamo-pituitary gonadal axis: male

Answer 1

hypothalamus -> GnRH -> anterior pituitary -> LH and FSH -> stimulate testis to secrete testosterone and inhibin -> inhibin has negative feedback on pituitary and hypothalamus

Question 2

3 phases of the 28 day menstrual cycle in females

Answer 2

follicular phase, ovulation, luteal phase

Question 3

hypothalamo-pituitary gonadal axis: female during follicular phase

Answer 3

hypothalamus -> GnRH -> anterior pituitary -> LH and FSH -> stimulate ovaries to secrete oestradiol, progesterone and inhibin -> inhibin has negative feedback on pituitary and hypothalamus

Question 4

hypothalamo-pituitary gonadal axis: female during ovulation

Answer 4

hypothalamus ->huge secretion of GnRH -> anterior pituitary -> huge LH surge and some FSH secretion -> cause ovulation and stimulate ovaries to secrete huge amounts of oestradiol -> positive feedback on hypothalamus to secrete more GnRH

Question 5

2 routes of luteal phase in females

Answer 5

if implantation does not occur, endometrium is shed in menstruation; if implantation does occur, pregnancy

Question 6

define infertility and how many people it affects

Answer 6

inability to conceive after 1 year or regular unprotected sex; 1 in 6 couples

Question 7

infertility abnormal causes: % in male, female or unknown

Answer 7

male 30%, female 45%, unknown 25%

Question 8

hypothalamo-pituitary gonadal axis: primary gonadal failure causing infertility

Answer 8

hypothalamus -> high GnRH -> anterior pituitary -> high LH and FSH -> low testosterone/oestradiol -> inhibin has negative feedback on pituitary and hypothalamus

Question 9

hypothalamo-pituitary gonadal axis: hypothalamus or pituitary disease causing infertility

Answer 9

hypothalamus -> no/little GnRH (can’t be measured in circulation as not present) -> anterior pituitary -> low LH and FSH -> low testosterone/oestradiol -> inhibin has negative feedback on pituitary and hypothalamus