Hellkatz: Male Reproductive Physiology Flashcards
What is spermatogenesis?
production of mature haploid spermatozoa from spermatogonial sperm cells
What’s unique about male germ cells?
Capable of producing cells that undergo mitosis
Able to produce germ cells that differentiate into spermatozoa throughout life.
When do mitosis and meiosis occur in spermatogenesis?
Mitosis begins in the embryo
Mitosis and meiosis occurs through adult life
Where does spermatogenesis occur?
seminiferous tubules of testes
What’s a spermatogenic wave?
time it takes for reappearance of same stage w/in given segment of seminiferous tubule
*spermatogenesis is staggered throughout hte seminiferous tubule so ALL developmental phases occur at one time
What is the purpose of spmeratogenic waves?
ensures that spermatozoa are produced continuously & mature sperm are always available
How long is the total spermatogenesis cycle?
64 days
How many sperm are produced daily?
100 milion
What influences spermatogenesis?
directly proportional to testosterone levels
*decreases in older age goups
What regulates testosterone secretion?
NFB from testosterone and inhibin
Produces testosterone
testicle
produces DHT
prostate
produces dihydrioepiandrostendione
adrenal
Where are SHBG made and what do they do?
made in liver and sertoli cells, bind androgens and estrogens
What steroid receptor acts as a TF?
Androgen Receptor
What nourishes developing sperm and secretes androgen binding protein and inhibin?
sertoli cells
What stimulates sertoli cells leading to sperm proliferation and differentiation?
Testosterone and FSH
What does inhibin do?
inhibits FSH from AP
What promotes muscle building, bone growth and Na and water retention?
androgens
What is andropause?
androgen def w/ aging
Aging> decreased testosterone> decreased muscle mass and increased abdominal fat
What happens to testicular function w/ andropause?
loss of spermatocytes, Leydig cells, Sertoli cells
decrease of testosterone production
compensatory increases in secretion of GnRH and gonadotropins (FSH and LH)
Erectile dysfunction, weight gain and gynecomastia are all sxs of…
andropause (d/t shift in estrogen: testosterone ratio)
How do you dx andropause?
measure morning total testosterone
What are the normal circulating levels of testosterone in males and females?
Males = 0.6 mcg/dL Females = 0.03 mcg/dL
What are the androgenic effects of hormone replacement?
Hypogonadism Hypopituitary f(x)
What are the anabolic effects of androgens?
muscle building
Promotes prot synth → incr. muscle mass & strength [Counters glucocorticoid effects]
What type of androgen therapy is good for reversing protein loss?
anabolic > androgenic
opposite is good hormone therapy
What is used for testosterone hormone replacement?
Methyl testosterone (testosterone analog)
Hepatotoxicity, acute cholestasis and increased tumor incidence w/ chronic use are SE of..
methyl testosterone
What synthetic androgen is used to promote muscle growth and has low risk of hepatotoxicity?
Oxandrolene
Growth interrruption, priapism, jaundice, hypogonadism, aggressive behavior are se of ….
synthetic androgens
Why do synthetic androgens have so many SE?
Bind to MANY different receptors (glucocorticoid, progesterone, estrogen)> multiple effects
arromatization of steroids to estradiol compounds> adverse estrogenic efffects
What are adverse effects of anabolic steroids in men?
- Gynecomastia
- Testicular shrinkage/ reduce sperm count
- Impotence
- Baldness
What are adverse effects of anabolic steroids in women?
- Menstrual irregularities
- Clitoris enlargement
- Increase in facial & body hair
What is the purpose of medical castration drugs?
interfere w/ precocious puberty
tx androgen dep cancers
reduce libido
What should you use if your goal is to shut down the HPO axis?
GnRH agonists/antagonists (don’t wipe out locally produced androgens in other tissues–prostate)
What should you use if your goal is to reduce androgen signaling in the prostate gland?
androgen receptor antagonists or 5 alpha reductase inhibitors
What drug is used to reduce excessive sex drive in men, and treat hirsuitism in women.
Cyproterone acetate
What drug is used to tx prostate cancer but may cause gynecomastia and be hepatotoxic?
Flutamide
bicalutamide
What is a diuretic that is used to tx hirsutism or acne in women?
spironolactone
What is the difference between single/pulsatile GnRH agonists vs continuous GnRH agonists?
Single/pulsatile → stimulatory
Continuous → inhibitory but has **IMMEDIATE androgen flare
What drugs bind GnRH receptors → block action of GnRH → reduced FSH/LH → reduced testosterone production by testes and have NO immediate androgen flare?
GnRH antagonists
What drug is used to assess gonadal response and can improve sperm numbers after 3-6 mos of pulsatile infusion?
Gonadorelin
What drug is used to tx advanced prostate cancer and BPH?
Degarelix
What is a synthetic GnRH analog used to tx gonadotropoin dependent precocious puberty?
Leuprolide
What drug is used to tx ovarian hypersecretion?
Ganirelix
cetrorelix
What drugs inhibit the conversion of testosterone to DHT?
5 alpha reductase inhibitors
What is androgen specific for growth and maintenance of the prostate gland?
DHT
What is used to tx BPH and male patterned baldness?
Finasteride
What is used to tx BPH, male pattern bladness, and hirsutism in women?
Dutasteride
slower onset and longer t1/2
What is the physiology of an erection?
1) PS stimulation causes production/release of Nitric Oxide (NO)
2) NO binds membrane receptors in vascular smooth muscles
3) induces increase in intracellular cGMP
4) cGMP promotes arteriole dilation which causes penile engorgement (tumescence).
5) Phosphodiesterase 5 in vascular smooth muscle degrades cGMP
6) Vasodilation ensues which results in a flacid penis.
What drugs prevent the degradation of GMP and can cause HA, flushing, dyspepsia and nasal congestion?
Sildenafil (viagra), verdena fil and tadalafil
What drugs should not be used w/ other nitrates or alpha blockers?
sildenafil
