#36 Flashcards
(19 cards)
What are the testes mainly made out of?
seminiferous tubules
what cells secrete testosterone?
leydig cells
How is testosterone secreted during fetal development?
placental hCG acts on leydig cells to secrete testosterone leading to male sex differentiation
How is testosterone secretion controlled at puberty?
GnRH from hypothalamus acts on anterior pituitary to secrete LH to act on leydig cells to secrete testosterone. Leads to pubertal growth and maturation
a gymnast is taking high levels of testosterone. After a few months, what would his levels of GnRH, LH, and FSH be?
all low. The testosterone is causing a negative feedback on all of them
What are the side effects of steroids in men?
shrinkeage, enlarged prostate, headached, aching joints, aggression, etc
problems with testosterone in women?
reduced breast size, enlarged clitoris, increased body and facial hair, deepened voice, menstrual problems
Where are sperm developed?
sertoli cells, which combine to make the seminiferous tubules
control of spermatogenisis
testosterone causes sertoli cells to undergo spermatogenisis, and after they do they secrete INHIBIN. inhibin is hegative feedback on FSH secretion.
blood testes barrier
sertoli cells contain tight junctions and provide a protective barrier against potential contamination. Disruption causes spermocyte death and sterility
What substance disrupts the blood testes barrier?
cadmium. Mostly comes from smoking.
DBCP pesticide- what does it do?
causes male infertility without leydig or sertoli cell destruction
2BP what does it do?
cleaning solvent that may impact fertility in males
nervous system in penis at rest
sympathetic, NE is released at arterioles and causes continual vasoconstriction
nervous system during erection
decreases SNS, increased PNS input to arterioles. Nitric oxide release triggers vasodilation, filling of vascular compartments with blood
Molecular pathway for erection
nitric oxide stimulates guanylyl cyclase which converts GTP to cGMP causing smooth muscles to relax and increasing bloodflow
how does viagra work?
Inhibits PDE-5, which breaks down cGMP. Keeps cGMP levels high so the smooth muscles stay relaxed
eaculation-emission stage
continued stimulation results in spinal reflex activation of sympathetic nerves that innervate prostate, seminal vesicles and reproductive ducts leading to the delivery of semen to the urethra
expulsion phase
semen in urethra triggers sympathetic reflex, a series of skeletal muscle contractions
