- musculocavernosus: large amount of erectile tissue (horse, dog, cat, human) - fibro-elastic: fibroelastic tissue with smaller amounts of erectile tissue --> sigmoid flexure that straightens (artiodactyls)

- surrounds urethra - terminates as glans penis - low pressure system to increase penile volume

- autonomic (sympathetic, parasympathetic) - sensory/motor via pudendal nerve

- flaccid - tumescence - stable erection - detumescence

- maintained by tonic contraction of smooth muscle in corpora - arteries supplying them under the influence of sympathetic adrenergic input - little blood enters vascular spaces

- psychic stimuli on brain, tactile stimuli on penis --> decreased sympathetic tone, increased parasympathetic tone - relaxation of penile arterioles and smooth muscle - increased formation of NO and cGMP --> mediates relaxation, blood flows into erectile corpora - venous drainage compressed (expansion of corpora, contraction of bulbospongiosus and ischiocavernosus mm)

- sympathetic tone increases, parasympathetic decreases - synthesis of NO and cGMP ceases - brief increase in corpus cavernosal pressure as smooth mm contracts under influence of noradrenalin - venous outflow re-established

Sperm transport, maturation Flashcards by Ali T-H

mechanism of sperm transport in species with retained phallus

mechanism of erection if lymphatic, not vascular

- semen transferred via groove along outside of phallus instead of tube in the middle

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2 types of penises

musculocavernosus: large amount of erectile tissue (horse, dog, cat, human)
fibro-elastic: fibroelastic tissue with smaller amounts of erectile tissue –> sigmoid flexure that straightens (artiodactyls)

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corpus cavernosa and tunica albuginea

paired corpus cavernosa enclosed in tunica albuginea
separation of sides in incomplete
high pressure system that supplies rigidity

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corpus spongiosum

surrounds urethra
terminates as glans penis
low pressure system to increase penile volume

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Innervation of penis

autonomic (sympathetic, parasympathetic)

- sensory/motor via pudendal nerve

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What is responsible for keeping the non-erect penis within the prepuce

Paired retractor penis muscles

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Why can’t penis in juveniles be fully extended

Penis is attached to the prepuce (attachment later breaks down)

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4 phases of erection

flaccid
tumescence
stable erection
detumescence

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Flaccid state

maintained by tonic contraction of smooth muscle in corpora
arteries supplying them under the influence of sympathetic adrenergic input
little blood enters vascular spaces

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Erection

psychic stimuli on brain, tactile stimuli on penis –> decreased sympathetic tone, increased parasympathetic tone
relaxation of penile arterioles and smooth muscle
increased formation of NO and cGMP –> mediates relaxation, blood flows into erectile corpora
venous drainage compressed (expansion of corpora, contraction of bulbospongiosus and ischiocavernosus mm)

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Detumescence

sympathetic tone increases, parasympathetic decreases
synthesis of NO and cGMP ceases
brief increase in corpus cavernosal pressure as smooth mm contracts under influence of noradrenalin
venous outflow re-established

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2 components of ejaculation

emission

- expulsion

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What is ejacation mediates by

mediated by spinal reflexes within spinal ejaculation generator
integrates sensory inputs from genitalia –> triggers ejaculation

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Sensory receptors

Located on penile skin, glans, urethral, within the corpus cavernosum –> information sent via dorsal penile and pudendal nerve

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emission in ejaculation

getting all components of ejaculation into pelvic urethra
secretion of fluids from accessory glands, contraction of cauda epididymis and vas deferens containing sperm, and closure of sphincter at bladder neck and external urethral sphincter
parasympathetic: stimulates secretion of fluids bu accessory glands
sympathetic: muscle contraction of accessory glands to expel fluid, cauda epididymus, and vas deferens to move sperm - contracts bladder and external urethral sphincters

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expulsion in ejaculation

continued sexual stimulation causes further activation of spinal systems - reaching threshold triggers expulsion
rhythmic contractions of urethral smooth muscle and straiated bulbospongiosus muscle act to expel semen from urethra
rhythmic contractions of ischiocavernosus, levator ani, and external urethral sphincter muscles
followed by refractory period where sexual arousal is inhibited

activation of sperm motility

kept immotile during storage in cauda, activated during emission and ejaculation when mixed with accessory sex gland fluids
show progressive motility
activated motility is when they are activated by dilution of sperm in accessory sex gland fluid

sperm transport

transport is a function of their motility and mechanical movement by contractions of female
female influences motility by spatial constraints, epithelial cell surface characteristics, physical properties of tract secretions

factors that influence the mechanisms and speed of sperm transport to the site of fertilization (4)

species variation in size, morphology of sperm
duration of estrus and timing of ovulation
anatomical site of sperm deposition (number of barriers)
lifespan of sperm within female tract

rapid sperm transport

some sperm found in oviduct within minutes (usually non-viable)
due to contractions of female tract and changes in intraluminal pressure
these sperm not involved in fertilization process

sperm transport though cervix

cervical mucus prevents passage of appreciable amounts of seminal plasma into upper tract
sperm must get through mucus, cervical folds (deep crypts) –> privileged pathways (sperm in crypts are more likely to reach uterus)
cervical mucus is sperm reservoir
cervix is selective barrier to filter out weak/abnormal sperm

sperm transport through uterus and oviduct

uterine contractility is important for distributing sperm throughout uterus
presence of the male, coitus, and products within the semen increase uterine contractions
prostaglandins in seminal plasma increase myometrial contraction
estrogen in seminal plasma increases uterine contraction
viable sperm can bind to avoid discharge back through cervix

functions of sperm storage

maintain sperm viability
serve as site of capacitation
synchronize final sperm maturation (capacitation) with ovulation
selection of highest quality sperm

where is sperm stored in female

-caudal isthmus of oviduct (fertilization in ampulla of oviduct)

sperm binding

- mediated by glycans on surface of ciliated oviductal epithelial cells that interact with surface proteins (lectins) on seminal plasma membrane - lectins are products of accessory glands that coat sperm during emission, ejaculation

when can sperm bind in the reservoir

before they have undergone capacitation --> binding prevents Ca uptake by serum, which prevents capacitation changes and maintains cell in statsis, preserving viability

sperm selection process

- ones in lower tract are removed by efflux - others are eliminated by leukocytes that invade the uterine lumen in response to insemination - excess sperm in oviduct removed by flow out of peritoneal cavity - many potential sites of selection (oviduct)

what do oviductal binding sites select sperm for

- not capacitated - not acrosome reacted - morphologically superior - chromatin intact (no DNA fragmentation)