Lecture 20 - Male Reproductive Physiology Flashcards
SRY gene
Sex determining region of the Y (aka TDF - testes determining factor)
transcription factor
needed for XY
AMH
anti-mullerian hormone - growth factor –regression of mullerian ducts
blocks progression to female pathway
Sertolic Cells
Make AMH
Leydig Cells
make testosterone
responsible for internal genitalia
DHT
external male genitalia
XO
gonadal dysgenesis - Turner’s Syndrome
YO
lethal
XXY
Klinefelters syndrome
gynecomastia
small testes, reduced fertility
Female pseudohermaphroditism
male gender identity
made too much androgen
Male pseudohermeaphroditism
female gender identity
male that had androgen resistance
When clinically does puberty start?
pulsatile GnRH secretion
LH
Leydig cells
stimulate testosterone synthesis and release (in response in GnRH)
FSH
sertoli cells
androgen binding protein (ABP)
inhibin synthesis
inhibin
hormones made in Sertoli cells responding to FSH
inhibits pituitary production and release of FSH
Activin
antagonizes inhibin at pituitary
enhances FSH secretion
17Beta hydroxysteroid dehydrogenase
enzyme in the testes that converts pregnenolone or androstenedione to testosterone
Where is cholesterol made?
liver
What does testosterone do?
1) activates androgen receptor
2) conversion of DHT by 5 alpha reductase
3) Conversion to estradiol by aromatase (CYP19)
What are the effects on men who do not response to estradiol?
either from aromatase defect of lack of estrogen receptor
epiphyses does not fuse and osteoporosis
if aromatase defect –treat with estradiol
What is testosterone bound to in circulation?
SHBG (sex hormone binding globulin - from liver)
only free T is active
Finasteride
competitive inhibitor of 5 alpha reductase
used for prostate cancer
HRE function
Hormone response elements
gonadotropin feedback spermatogenesis sexual differentiation anabolic effects libido
DHT function
prostate development
external virilization
sexual maturation at puberty
baldness
The administration of clomiphene (a SERM) would most likely lead to….?
Not done here
