Reproduction - male reproduction Flashcards
At the pituitary level, what does inhibin B inhibit the release of?
FSH
At the pituitary level, what does activin stimulate?
Release of FSH and LH
In male reproduction what cells produce inhibin B, and what stimulates its expression?
Sertoli cells; FSH stimulates its expression
Where is activin expressed, and aside from being activating to gonadotrophic hormones what else does it do?
Activin is expressed in pituitary and testes and also generates the GnRH receptor which makes the ituitary more sensitive to GnRH
FSH effect on: Spermatogenesis? Sperm motility? Growth of seminiforous tubules? Androgen binding protein? Aromatase? Inhibins? Growth factors?
Increases to all of them
LH effect on: Steroidogenesis ANdrogen generation StAR protein Leydig cell growth
also increase
What is the enzyme that converts DHEA to androsteinedione
3b-HSD
How can androstendione be converted into Testosterone? And what else can it be turned into?
17bHSD (type III in males)
Can also be used to make estrone
how do we get DHT from T
5a reductase
What can DHT be turned into
3a diol or 3b diol
How is excreted testosterone excreted
as 17 ketosteroids and DHT – conjugated to wwater solube forms and excreted
What hormones are responsible for beard growth, sebum formation, and prostate generation
DHT
What hormoens are responsible for male pubertal development
DHT and T
What hormones are responsible for sperm production
T, DHT, E
What hormone is responsible for raising VLDL and LDL and lowering HDL
T
What hormone is responsible for RBC generation
T
What hormone is responsible for increase in muscle mass
T
What hormone is responsible for increase in abdominal visceral fat
T
What hormones are responsible for bone protection
T and E
What hormone is responsible for male voice
T
What hormones are responsible for male behavior
T, E, DHT
what hormones are responsible for feedback inhibition of gonadotropic secretion
T, E, DHT
What hormone is responsible for intrauterine differentiation of penis, scrotum, urethra, and prostate
DHT
What 3 things does T directly support development of in utero (fetal development)?
Epididymis, vas deferens, seminal vesicles (internal tract from wolffian duct)
What 6 things does T directly support development of at puberty
Penis, seminal vesicles, musculature, voice, skeleton, spermatogenesis
What 3 things does DHT support in utero
Penis, penile urethra, prostate, and scrotum
What 4 things does DHT support at puberty
Scrotum, prostate, male pattern hair distribution, sebaceous glands
4 steps of testicular descent
Embryonic position (up), transabdominal phase , inguinoscrotal phase (migration), elongation of cord
2 major parts of testes
seminiforous tubules, scrotum
testicular blood flow and why it is important
Sperm are picky and like it 1-2 degrees cooler then body temp - thus there is a testicular artery posed spirally along the vein, which transfers warm arterial blood heat to venous blood prior to contact with seminiforous tubules
Peritubular testes space
Leydig cells, myoid cells, an vascular supply
Intratubular testes space
Sertoli cells, developing germ cells, and lumen where the mature sperm are released
Inhibin in leydig cells
Augments LH induced testosterone production in Leydig cells
Activin in leydig cells
Inhibits testosterone production in leydig cells
Spermatogenesis
The process by which spermatogonia become 4 haploid spermatids
Spermiogenesis
The maturation of spermatids into spermatozoa - spermatids differentiate into flagellated spermatozoa. Nuclear condensation, shrinkage of the cytoplasm, formation of acrosome, development of tail
Spermiation
The release of spermatozoa from sertoli cells into lumen - most remaining cytoplasm is removed and residual body is formed.
Where do spermatogenesis, spermiogenesis, spermiation occu
In the seminiferous tubule
Can spermatazoa always move
Nope, they are immobile in the seminiforous tubule and passively move from this to rete testis
Where do spermatozoa continue to matue, and what happens to their structure as they go? Their ability to move?
Mature along the tubule of epididymis - acts as a reservoir for sperm, and important fo sperm maturation. While storedin epididymis, sperm gain mobility and lose most of their cytoplasm, and crosome is stabilized (decapacitation). They gain mobility.
Acrosome
Sperm cap that contains hydrolyzing enzymes used to penetrate ovum.
Seminal vesicles and what they secrete
Paired structures that lie inferior to bladder on either side of urethra that form ejaculatory duct together; add nutrients (fructose, citric acid, etc to keep sperm alive), prostaglandins (facilitate sperm transport by getting uterine contractions), buffer (to keep pH in narrow range to promote survival and mobility)
Prostate and what it secretes
Alkaline secretions to neutralize vaginal pH, and proteolytic enzymes to help liquefy semen
Cowper’s/bulbourethral gland and what it secretes
Sits below prostate, , secretes mucus into urethra upon arousal (can contain some sperm)
Benign prostate hyperplasia
Prostate is just gonna keep growing - it can cause pain, and eventually develop into cancer with age. Pathology is unclear but BPH can increase tissue PSA by 10 and a tumor will increase it in the serum. Possibly this is due to increased sensitivity to testosterone due to increased androgen receptors.
Flaccid state in penis
SNS action keeps helicine arteries contracted – restricts blood flow.
What happens in an erection
PSNS activity leds to relaxation of smooth muscle in corpora cavernosa and corpus spongiosum → increase in blood flow, and engorgement results in swelling. Ach and NO lead to further vasodilation.
How does viagra work
Inhibits PDE’s - so you are able to maintain an erection - but can cause heart problems since this is not specific to penile circulation.
What branch of ANS controls emission
SNS
What is involved in ejaculation
Peristaltic rhythmic contractions via smooth muscle of portions of vas deferens, seminal vesicles, prostate. Ejaclation is a spinal cord reflex triggered by entry of semen into bulbous urethra frm prostatic urethra – rhythmic contractions of ischiocavernosus and bulbospongiosus muscles propel semen through urethra
Hypergonadotrophic hypogonadism
High LH/FSH, low T/DHT - such as enzyme deficiencies in steroid hormone bioynthesis
Hypogonadotrophic hypogonadism
Low GnRH, low LH/FSH, low T/DHT
Most common cause of subfertility in men
Varicocele (dilated scrotum veins)
Post testicular causes of male infertility
Ductal obstructions, premature ejaculation, impotence
