Flashcards in Week 7.0 - Coitis and fertilisation Deck (77)
How long does it take for spermatogonia to mature into spermatozoa?
-upto 74 days (50 in testis 12-24 in epididymis)
When does spermatogenesis begin/end?
-From puberty until death
How many of the sperm produced per day become viable sperm?
Does production of sperm stay the same throughout life?
-Decreases in quantity and quality with age
Which hormone acts on the leydig cells? What is the result of this?
-Production of testosterone
Which hormone acts on the sertoli cells? What is the result of this?
-Antigen binding protein production leading to the concentration of testosterone in luminal fluid enabling spermatogenesis
If the pituitary gland is removed, how is spermatogenesis stimulated?
-FSH and testosterone
What is the function of oestrogen in the testis?
-Increase sperm viability
What is nuclear condensation and when does it happen?
-Extrusion of the cytoplasm and condensation of the nucleus from spermatid to spermatozoon
What does the acrosome contain? Why?
-Golgi apparatus and hydrolytic enzymes to enable sperm to penetrate ovum
Identify the main feature of the midpiece of a spermatozoon
Why is this needed?
-Mitochondria packed around either side
-Motility is a highly energy dependant process
What is the tail of a sperm made from?
-Flagellum produced by microtubules
What signals for the cytoplasm and organelles to be stripped from the permatid?
What is different between the mature spermatozoa in the seminiferous tubules and the mature spermatozoa in the epididymis?
-Lack motility in the seminiferous tubules
What is spermiation?
-Release of spermatozoa from sertoli cells into seminiferous lumen
How are spermatozoa transported from seminiferous lumen to epididymis?
-Testicular fluid (produced by sertoli cells) and peristaltic contraction
How long can mature spermatozoa stay in the epididymis?
-Several months, eventually phagocytosed
How do the spermatozoa get into ductus deferens?
-Upon sexual arousal the epididymal wall contracts and expels the sperm into the ductus deferens
What are the phases of coitus?
What is the refractory period in males?
-After ejaculation it is not possible to ejaculate again upon further stimulation
Describe the excitement phase of the male sexual response
-Sensory and psychological stimulation
-Inhibition of sympathetic outflow (thoracolumbar)
-Activation of parasympathetic outflow (sacral)
-Ach-> M3 on endothelial cells of penile bvs -> increased Ca-> activation of eNOS -> NO production
-Arterial vasodilation in corpora cavernosa
-Increased penile blood flow
-Penile filling (full of blood but not erect)
-Penile tumescence (erection)
What happens to the testes and scrotum upon sexual arousal?
-Testes elevate and engorge and scrotal skin thickens and tenses
Describe the plateau phase of male sexual response
-Activation of sacrospinous reflex
-Contraction of ishiocavernosus -> compresses crus of penis and impedes venous return -> venous engorgement
-Rise in intracavernosus pressure higher than systolic pressure -> decreased arterial inflow
-Stimulation of secretion from accessory glands
-Loss of erection unlikely
Which accessory glands are stimulated in the plateau phase of male sexual response?
What are the two stages of orgasmic phase in male sexual arousal?
Describe the emission stage of orgasmic phase in male sexual response
-Stimulation of sympathetic reflex
-Contraction of smooth muscle in ductus deferens, seminal vesicle and prostate
-Internal and external urethra contracts
-Semen becomes pooled in urethral bulb
Describe the ejaculation stage of orgasmic phase of male sexual response
-Sympathetic spinal reflex with cortical control
-Further contraction of glands and ducts and sphincters
-Filling of urethra stimulates pudendal nerve-> contractions of the genital organs, ischiocavernosus and bulbocavernosus -> expulsion of semen
Describe the resolution phase of the male sexual response
-Activation of sympathetic outflow
-Contraction of arteriolar smooth muscle in corpora cavernosa
-Increased venous return
-Detumescence and flaccidity
-Testes descend and scrotum thins and relaxes
-Refractory period entered
Describe the excitement phase of the female sexual response
-Sensory and psychological stimulation
-Activation of parasympathertic outflow; inhibition of sympathetic outflow
-Vasocongestion causes vaginal lubrication to begin
-Clitoris becomes engorged with blood
-Uterus elevates, inner 2/3 of vagina lengthens and expands
-Increased muscle tone, HR and BP