PHYS-Male Repro Physiology Flashcards
How do testosterone levels fluctuate from the fetal period to puberty and old age?
theres a surge in the fetal period for sex differentiation
another neonatal surge because the cells are differentiating
final puberty surge that causes puberty and that gradually declines till you die
what happens at puberty to start the production of sex androgens?
there is a pulsatile secretion of GnRH resulting in a pulsatile secretion of FSH/LH that results in testosterone production
what happens if the secretion of GnRH is continuous rather than pulsatile?
the constant production of sex androgen inhibits the cycle via negative feedback decreasing LH/FSH and testosterone
what stimulates leydig cells? what is their function once stimulated?
LH stimulates –> leydig –> testosterone production from cholesterol
where do leydig cells get their cholesterol?
de novo or from circulation
what stimulates sertoli cells?
FSH –> sertoli cells –> spermatogenesis along with
several endocrine and exocrine and maintenance functions
what are the endocrine functions of sertoli cells?
secretes AMH, inhibin, and aromatase
what are the exocrine functions of sertoli cells?
aqueous fluid for sperms transport to the epididymis
produce androgen binding protein
what is the function of androgen binding protein?
binds and concentrates testosterone in the sertoli cells
what are the supportive functions of the sertoli cells?
prodvide nutrients for sperm and form tight junction to prevent autoimmunity
what are the steps of spermatogenesis starting with a spermatogonia?
spermatogonia –> mitosis –> primary spermatocyte –> meiosis I –> secondary spermatocyte –> meiosis II –> spermatids –> nuclear and cytoplasmic changes –> spermatogonia (mature sperm(
what are the parts of sperm? what does each part do?
head-contains nucleus and acrosome
tail-motility
what is the function of the acrosome?
contains hyaluronidase and proteolytic enzymes to breakdown the outer layer of egg
what does the tail contain to make it motile?
axoneme, mitochondria, dynein ATPase
what is the ideal sperm environment? life span?
alkalina, lower than body temp, 1-2 months
what is the pathway of sperm from creation through ejaculation?
seminiferous tubule –> epididymis –> vas deferens –> ejaculatory duct –> nothing (hangs out for awhile –> urethra –> penis
what is the function of the epididymis?
store sperm, educate them on motility, mature sperm
“decapitation” to prevent premature acrosome activation
what is the function of the vas deferens?
sperm storage in ampulla till sex
secretes fructose and citrate to nourish sperm
what is the function of the seminal vesicle?
to secrete the fluid part of semen composed of fructose, prostaglandins, and citrate important for fertilization
what is the function of the ejaculatory duct?
empty sperm into prostatic urethra and stores it until ejaculation
what is the function of the prostate?
secrete an alkaline fluid
helps promote motility and neutralizes acid to help with fertilization
what is the function of the bulbourethral glands?
secrete clear fluid to lubricate urethra
what is the main component of sperm? what else is there?
fluid from seminal vesicle 60% (SEMINal vesicle makes semen)
alkaline prostate fluid 30%
10% sperm
some bulbourethral gland fluid
what are the two negative feedback loops in the HPT axis?
testosterone from leydig inhibiting GnRH and FSH/LH release
inhibin from sertoli inhibiting GnRH and FSH/LH
what hormones are required for spermatogenesis?
testosterone (via LH) FSH GH estrogens DHT plays a little role i think
what is the potency order of male androgens?
DHT>testosterone>androstenedione
LH kicks off testosterone production by upregulating what enzyme where?
cholesterol desmolase in the leydig cells
what converts testosterone to DHT in target tissues?
5a reductase
what is the function of GnRH
release FSH/LH from anterior pituitary
what is the function of LH?
LH –> leydig –> testosterone
what is the function of FSH?
FSH –> sertoli –> spermatogenesis
what is the function of testosterone early on?
development of internal male genitalia
descent of testes
what is the function of testosterone during puberty?
secondary sex characteristics
acts on sertoli cells to assist with spermatogenesis
what are the secondary sex characteristics brought on by testosterone?
growth closure of epiphyseal plates muscle growth deepening of voice pubic/armpit hair libido penis growth increased BMR increased RBCs
what is the function of DHT early on?
development of male external genitalia
what is the function of DHT during puberty and beyond?
sebaceous gland, prostate growth, male pattern baldness
a male comes in with c/o baldness and dysuria due to an enlarged prostate. what should you give em?
a 5a reductase inhibitor (finasteride)
what is the function of inhibin
produced by sertoli cells to inhibit FSH/LH/GnRH
what is the function of AMH
regression of mullarian duct during development
what is the function of estradiol?
bone maturation, growth, breasts, role in spermatogenesis
what nervous system and nerve are responsible for erection?
parasympathetic via pelvic splanchnic nerves –> inferior hypogastric plexus –> prostate subplexus nerves
what substances are released and how do these cause an erection?
ACh, NO, VIP –> increase cGMP –> smooth muscle relaxation –> vasodilation in helicine arteries –> engorgement cuts off venous return –> boner
what nervous system/nerves are involved in emission?
sympathetic via pudendal nerve
what is emission?
movement of semen towards internal urethra via smooth muscle contractions
what nervous system is involved in ejaculation?
sympathetic via pudendal nerve
what occurs during the process of ejaculation?
rythmic contractions of bulbospongiosus and ischiocavernosus muscles increases pressure forcing semen out
what causes erectile dysfunction? how would you treat this?
HTN, DM, atherosclerosis
a phosphodiesterase inhibitor –> increases cGMP
normally phosphodiesterase breaks down cGMP
what is a cause of primary hypogonadism?
where is the problem arising?
what are testosterone, FSH, LH, and estrogen levels?
what are symptoms?
Klinefelter syndrome XXY
the testes are inadequate at producing testosterone
low testosterone, high FSH/LH, high estrogen
woman features, boobs, fat around hips, reduced hair
seminiferous tubule dysgenesis
what is a cause of secondary hypogonadism?
where is the problem arising?
what are testosterone, FSH, LH, GnRH levels?
what are symptoms?
nonfunctioning pituitary tumor
anterior pituitary
low, low, low, high
bitemporal hemianopia (loss of vision in lateral fields), HA
what is a cause of secondary (but actually tertiary based off endocrine) hypogonadism?
where is the problem arising?
what are testosterone, FSH, LH, GnRH levels?
what are symptoms?
GnHR neurons fail to migrate to hypothalamus during development
hypothalamus
low low low low
delayed/absent puberty, infertility
what causes enlarged prostate? sx? treatment?
DTH and age
urinary issues
5a reductase inhibitor inhibits testosterone –> DHT
