Male Reproductive Physiology Flashcards
sexual excitement causes CNS activation of ___ neurons innervating internal pudendal arteries, causing release of nitric oxide (NO)
parasympathetic
During ejaculation, spinal reflex is initiated over sympathetic nerves serving genital organs, resulting in: (1)
ductus deferens, prostate, and seminal glands contract and empty contents into prostatic urethra; bladder internal sphincter muscle constricts, preventing expulsion of urine or reflux of semen into bladder
During ejaculation, spinal reflex is initiated over sympathetic nerves serving genital organs, resulting in: (2)
Semen in urethra triggers spinal reflex through
somatic neurons; bulbospongiosus muscles undergo rapid series of
contractions that cause expulsion of semen
latent (refractory) period
time during which man is unable to achieve another orgasm
erectile dysfunction
parasympathetic nerves of penis release too little NO, leading to inability to attain erection
spermatogenesis
process of forming male gametes; occurs in seminiferous tubules
Seminiferous tubules
consist of a thick stratified epithelium surrounding a central fluid-filled lumen containing four important types of cells
Seminiferous tubules contain four important types of cells:
sustenocytes, spermatogenic cells, myoid cells, interstitial endocrine cells
sustenocytes
large columnar cells act as supporting cells and play role in sperm formation
spermatogenic cells
cells that are surrounded by sustentocytes and give rise to sperm
myoid cells
smooth muscle-like cells surrounding seminiferous tubule that contract to squeeze sperm and testicular fluid through tubules
interstitial endocrine cells (Leydig cells)
produce androgens and some estrogen
three steps of spermatogenesis
mitosis of spermatogonia, meiosis, spermiogenesis
mitosis of spermatogonia (stem cell)
forms two spermatocytes
meiosis
spermatocytes form secondary spermatocytes, which form spermatids
spermiogenesis
spermatids become sperm
spermatogonia
stem cells that are in direct contact with epithelial basal lamina that divide more or less continuously by mitosis
After puberty, each division of stem cells produces:
Type A daughter cells (remain at basal lamina to maintain pool of dividing germ cells); Type B daughter cells (move toward lumen and develop into primary spermatocytes)
meiosis
spermatocytes to spermatids
spermiogenesis
spermatids to sperm
contains hydrolytic enzymes that enable sperm to penetrate egg
acrosome (found in head of sperm)
sperm midpiece
metabolic region containing mitochondria that produce ATP to move tail
role of sustenocytes
large supporting cells extend from basal lamina to tubule lumen and surround developing spermatogonium
sustentocytes contain tight junctions that divide tubule into two compartments
basal and adluminal
basal compartment
basal lamina to tight junctions; spermatogonia and primary spermatocytes located here
adluminal compartment
internal to tight junction; area where meiotically active cells and tubule lumen are located
tight junctions form the blood testis barrier
prevents sperm antigens from escaping into blood and causing activation of immune system
testicular fluid
rich in androgens and metabolic acid; secreted by sustenocytes
androgen-binding protein (ABP)
keeps testosterone levels high to stimulate spermatogenesis
referred to as the hypothalamic-pituitary-gonadal (HPG) axis
sequence of hormonal events involving hypothalamus, anterior pituitary gland, and testes that regulates the production of gametes and sex hormones
testosterone is converted to what in the prostate
digydrotestosterone (DHT)
testosterone is converted to what in some brain neurons
estradiol
