Sperm Motility, Epididymal Transport, Erection, and Ejaculation Flashcards
Which components of sperm are important for sperm motility?
all components
Function of laminated columns of mid piece?
give neck region flexibility allowing for lateral movement from side to side during flagellar beating
Function of the mitochondrial helix of mid piece?
metabolic powerplant; ATP production
Function of course outer fibers?
fibrous sheath surrounds the tail except at the end of the tail
What is the metabolic powerplant?
the mitochondrial helix where ATP is produced to allow for fuel source for motility
Function of axoneme?
the axial filament complex that originates from the distal centriole with the same organization of cilia and flagella but it has a 9+2 complex of microtubules and extends through the entire length of the tail of the sperm
Where is the dynein arm located?
axoneme
9+2 complex?
9 pairs of MT surrounding a core of 2 MT
Does the principal piece have the 9+2 complex?
no, it doesn’t have any mitochondria
How does MT sliding in the sperm tail create motility?
occurs as a result of the sliding of those microtubules (derived from ATP derived from ATPase); the dynein arm detaches in the presence of ATP and shortens; once that energy is made, the dynein arm tilts and elongates to attach to a lower side and then shortens and returns to its original position; this generates the sliding forces that move the tail in a helical fashion
To provide energy for motility, sperm must __.
metabolize
anerobic metabolism?
glycolysis
aerobic metabolism?
TCA cycle
sperm metabolism?
through a series of enzymatic processes, they produce products that can enter glycolysis to enter TCA cycle to produce ATP
In sperm metabolism, can both fructose and glucose be utilized?
yes
sperm metabolism is dependent upon what?
temperature
the amount of ATP that can be produced depends on what?
the temperature of the environment
When temperature increases, motility ___.
increases
ATP is utilized for ___ and ____.
motility and substrate cycling
Some ATP is wasted in sperm metabolism by what process?
substrate cycling (glucose 6-phosphate to glucose)
Only a small amount of ___ is used to maintain the other important components of the sperm.
ionic gradients
Bulk flow alone will help get sperm out of the ST. How?
on the outside, it is lined with myoid cells that help through minor subtle contractions to assist with releasing bulk fluid flow)
What does bulk fluid flow help with?
to get out of ST as well as from the rete testis from the contractions of the mediastinum
What happens once sperm is released from the rete testis?
the sperm must be released from the vas deferentia (escapes from the cilia of epithelial to help bulk fluid flow to allow release of sperm)
Why can’t you rely on bulk fluid flow when sperm reaches the caput, corpus, and cauda?
because contractions of vas deferens propel sperm forward
Muscle contractions is which testes parts?
caput, corpus, cauda, vas deferens
Bulk fluid flow in which testes parts?
vas efferentia, rete testis, ST
Where is bulk fluid flow from in the rete testis?
fluid from ST and rete testis with some contractions of mediastinum
Where is bulk fluid flow from in the ST?
fluid from sertoli cells with contractions from myoid cells
Where is bulk fluid flow in the vas efferentia?
fluid from ST and rete testis with cilia on the epithelial cells
DHT?
dihydotestosterone
What does DHT affect?
the functional ability of principal cells
Importance of prinipal cells in caput and corpus epididymis environment?
lined with cilia and are important for lining the region of epididymis as well as secreted various products used to modify sperm so that as it progresses through, it will require the ability to become motile as well as fertile
Importance of ABP?
binding testosterone and delivering it to the epididymis to convert it to DHT
When sperm is in the epididymis (cauda) they are quiescent. What does this mean?
they don’t move so they can be modified as well as not to lose energy which is why contractions are used to move them
When will sperm be motile again?
when they are removed from the environment and the things surrounding them are diluted
What are the four functions of the epididymis?
1) maturation 2) concentration 3) Secretion 4) Transport 5) Storage
What is the ejaculatory reserve?
cauda epididymis
Up to __ days of sperm produced and stored in cauda.
4
What allows for repetitive ejaculations of a short period (only a limited number of reserves)?
Important for environment to be effective for arresting sperm metabolism before it is released into female reproductive tract
Factors conducive to sperm storage?
reduced pH; low oxygen high CO2; high K:Na ratio; low concentrations of energy substrates
hormones in caput?
tubal testosterone
hormones in corpus?
tubal dihydrotestosterone, vascular testosterone
hormones in cauda?
tubal DHT, vascular testosterone
Why are androgens needed for hormonal control of epididymis?
because we are talking about 2 different forms of testosterone (tubal and vascular)
erection?
process by which the penis elongates and becomes more rigid
emission?
movement of seminal fluids from the accessory sex glands into the colliculus seminalis so they can be mixed with sperm
ejaculation?
process by which sperm moves out of the colliculus seminalis through the urethra and expelled out the end of the penis
What two inputs play a major role in erections?
sensory and psychic inputs
sympathetic NS affects on erections?
involved in inhibited vasoconstriction
parasympathetic NS affects on erections?
allows blood to come in through the dilation of vessels and engorgement of the corpus cavernosum and contractions of ischiocavernosus to decrease venous outflow
What are the steps of penile erection?
1) flaccid penis 2) arousal 3) vasodilation (increased blood flow) 4) increased blood flow to cavernosus tissue and decreased venous outflow 5) ejaculation due to penile veins compressing from the build up of blood in penis corpus cavernosum 6) venous outflow
how is sperm transported from the epididymis to the pelvic urethra?
with sensory stimulation via muscle contractions the act of the posterior pituitary caused the release of oxytocin which acts on smooth muscle cells to let the sperm move up into the pelvic urethral area
Sympathetic NS leads to emission. how?
smooth muscle contractions of prostate, seminal vesicles, vas deferens, cauda; closure of sphincter to bladder; sperm moves to colliculus seminalis and mixed with accessory sex gland secretions
Parasympathetic NS leads to ejaculation. how?
striated muscle contractions of ishiocavernosus, bulbospongiosus, pelvic urethral; forceful contractions propel sperm mixed with ASG secretions out through an erect penis
intromission?
successful entrance of penis into vagina
explain the simple neural reflex of ejaculation.
when intromission occurs, there is specific and needed stimulation of the glans penis which can then alone be sufficient to induce ovulation
what two stimulants can alone be effective for inducing strong, forceful contractions needed for ejaculation?
temperature or pressure
semen components?
water, sperm, substrates, inorganic salts, proteins
minor contributions to seminal plasma?
testis, epididymis, vas deferens
major contributions to seminal plasma?
ampulla, seminal vesicles, prostate, cowpers (bulbourethral)
