Male endocrine

Question 1

2 main cell types in seminiferous tubule

Answer 1

1. leydig

2. sertoli

Question 2

what does leydig cell produce and respond to

Answer 2

produce: T

responds to: LH

Question 3

what does sertoli produce and respond to?

Answer 3

produce: and. binding homrone, inhibin, fluid, mullarian inhib. factor
responds to: FSH

Question 4

what stimulates FSH/LH and how

Answer 4

GnRH in pulsatile fashion

Question 5

what inhibits FSH/LH

Answer 5

T and inhibin

Question 6

how often does GnRh pulse

Answer 6

every 2-3 hours

Question 7

where does T feedback to and in what direction?

Answer 7

1. GnRH -ve

2. LH -ve

Question 8

what are T levels in testes and rest of body

Answer 8

testes - 100-600ng/ml

body 2/5-10 ng/ml

Question 9

what type of hormones are T and Est

Answer 9

steroid

Question 10

what are all steroid hormones derived from

Answer 10

cholesterol

Question 11

what is path from cholesterol to estrane and what are they converted to?

Answer 11

cholesterol>pregnane (progesteron)>androstane(androgens)>estrane(estrogens)

Question 12

what is path from cholesterol to pregnenolone

Answer 12

cholesterol side chain cleavage enzyme

Question 13

what is path from pregnenolone to androstendione

Answer 13

pronenolone(hydroxysteroi dehydrogenase)>progesterone(17a-hydroylase)>10-OH-progesterone(17,20 lyase)>androstenedione

Question 14

path from pregnenolone to DHEA

Answer 14

pregnenolone(17a-hydroxylase)>17-OH-preg(17,20-lyase)> DHEA

Question 15

of these 2 which is prominent

Answer 15

DHEA

Question 16

what is product f DHEA and androstendione and how

Answer 16

testosterone vis 17B-hydroxysteroid dehydrogenase

Question 17

what are 2 products of Test and via what enzyme

Answer 17

1. hihydrotestosterone (5a-reductase)

2. estradiol (CYP19 aromatase)

Question 18

how are most adrogens bound

Answer 18

sex hormone binding globulin>albumin>free

Question 19

when are 3 peaks of T in men

Answer 19

1. fetal - differentiation
2. neo-natal - ??
3. puberty on - reproduction

Question 20

where is T located in the body and how much

Answer 20

95% testes

5% peripheral

Question 21

what are 2 types of %a-reductase and where

Answer 21

type 1 - skin, body, scalp

type 2 - genitals + prostate

Question 22

what causes BPH

Answer 22

DHT via type 2

Question 23

what can be given as an inhibitor

Answer 23

finasteride - antagonist to type 2 5a-reductase

Question 24

which is more stable DHT or T

Answer 24

DHT

Question 25

how do DHT and T bind differently

Answer 25

DHT binds to same receptor but works on nuleas

Question 26

what is T responsible for in terms of phenotype

Answer 26

1. muscle mass
2. sex drive
3. GnRH
   4 spermatogenis
4. sexual differentiation
5. wolffian stimulation

Question 27

what is DHT responsible for in terms of phenotype

Answer 27

1. external virilization

2. sexual maturation at puberty

Question 28

what happens if we give continuous GnRh analogues

Answer 28

kills LH and FSH levels - slow precocious puberty and prostate cancer

Question 29

what would systemic injections of T do to sperm production

Answer 29

drop it