semen Flashcards
in a lab setting, if you took many sperm from the tail of the epididymus, and you placed them on a freshly ovulated ovum, would fertilization occur
no, because the sperm have not had any cholesterol or glycoproteins removed
where does sperm go after leaving the seminiferous tubule
enter the epididymis
what is capacitation
need to have proteins added/removed and phosphorylation of other proteins for fertilization to occur
what is the role of the epididymis
-some endocytosis of debris/dead sperm
-reabsorption of fluid from seminiferous tubule
what are the new proteins added in the epididymis
-PH-20: a hyaluronidase that helps break through cumulus (breaks extracellular matrix)
-CRISP1: sperm - zona pellucida interaction
what is the vas deferens
two tubes that carry sperm from epididymis to the urethra via peristalsis
-sperm held in ampullae until ejaculation
what are the glands in the male reproductive system
- seminal vesicles
- prostate
- bulbo-urethral (cowper’s)
-secretion from these glands mix with sperm to form semen
what does the prostate gland secrete
-prostate-specific antigen (PSA): helps dissolve coagulated semen; dissolving cervical mucous
what do seminal vesicles secrete
-semenogelin 1: sperm coagulation, increases viscosity of semen
what does the bulbo-urethral gland secrete
-mucus
-alkaline pH
-often secreted first to clean out urethra
how do sperm get close as possible to ovum
coitus
why is it that a drug designed to lower blood pressure has the effect of causing an erection (viagra)
-relaxes smooth muscle of blood vessels
-when vessels dilate in penis, increase blood flow into penis
how does an erection form
blood vessels of corpora cavernosa and corpus spongiosum become relaxed so that more blood can enter area
how does ejaculation work
-waves of peristalsis (likely due to oxytocin) increase in smooth muscle of epididymis, vas deferens, the glands and the urethra, which expel semen into urethral bulb
-sphincter leading to bladder closed
-bulbo cavernous muscle stimulated by sympathetic nervous system, producing forceful contraction
how does sperm move toward the oviduct
-sperm first encounter cervix
-sperm then ascend the uterus toward the oviducts with help from uterine contractions
how does capacitation involve initiating/increasing motility and preparing the acrosomal cap
- removal of cholesterol
- phosphorylation of proteins involved in motility
what is the removal of cholesterol due to
-albumin in vagina/cervix/uterus
-increasing motility
what is the removal of phosphorylation of proteins due to
activation of adenylate cyclase
the levels of HCO3- in the ovary tract are 5x higher than they are in the epididymis. what effect does the increase in HCO3- have on sperm motility
increases it
how does sperm capacitation work to enter the ovary tract
-HCO3- enters cell
-activates soluble AC
-increasing cAMP and PKA
-increasing phosphorylation of various proteins involved in motility
why does sperm need to become hyperactive
-they need to dislodge themselves from epithelial cells of oviduct
-need to increase motility to get through dense matrix of cumulus oophorus
-need to increase motility to get through zona pellucida
what happens to sperm in the presence of progesterone
opens Ca2+ channel
how does progesterone affect sperm
-activates CatSper channels on sperm
-resulting influx of Ca2+ leads to hyperactivation, chemotaxis, and acrosome reaction
-sperm comes in contact with progesterone, has receptors that respond to Ca2+ channels
how does low and high levels of progesterone affect hyperactivation
-low: attract and hyperactivation
-high: starts acrosome reaction
