Yan Male Flashcards
How many seminiferous tubules are there in a man?
900 seminiferous tubules
How long is the epididymis?
6 meters
When does spermatogenesis begin?
@ puberty–>like @ ages 12-14.
What are the 3 phases of spermatogenesis?
- Mitotic spermatogonial proliferation & differentiation
- meiotic division of spermatocytes into spermatids
- Haploid differentiation & morphogenesis of spermatids into spermatozoa
Roughly describe the process of spermatogenesis.
Basal membrane w/ developing primordial germ cells
PGM becomes spermatogonia
Spermatogonia multiply in number via mitosis
Spermatogonia become primary spermatocytes.
Primary spermatocytes enter meiosis I so that they can become haploid…become secondary spermatocytes.
Secondary spermatocytes via meiosis II become spermatids.
Spermatids differentiate into mature sperm.
How long does spermatogenesis take in humans?
72 days
Where does estrogen come from in men?
aromatized from testosterone in Sertoli cells
Why is reabsorption of luminal fluid in the epididymis important?
b/c then sperm can enter the epididymis concentrated, rather than dilute.
T/F ERß on spermatogonia, spermatocytes & Sertoli cells may mediate the actions of xenoestrogens (‘estrogenic endocrine disruptors’)
True. I have no idea why.
What are xenoestrogens?
estrogenic endocrine disruptors
Where are growth factors released from in the male? What is their effect?
secreted from Sertoli or germ cells
act on germ cells or somatic cells via their receptors
When FSH binds to Sertoli cells…what happens in terms of GH?
GH is released
this drives the development of germ cells
Stem cell–>meiotic cell–>haploid cell–>sperm
Describe negative feedback w/ testosterone production & w/ inhibin.
Testosterone produced by Leydig cells. When there is too much–>negative feedback to anterior pituitary & hypothalamus.
Inhibin is produced by Sertoli cells. It exerts negative feedback on anterior pituitary & hypothalamus.
Describe the maturation of the sperm in the epididymis.
120 million sperm are developed each day.
No motility when the sperm is in the head of the epididymis.
Some motility when the sperm is in the body of the epididymis.
Moderate motility when the sperm is in the tail of the epididymis.
What is the name for the head, body, & tail of the epididymis?
Head: caput
Body: corpus
Tail: cauda
What happens to the sperm when it is in the vas deferens?
this is a place where it can be stored for over a month w/ suppressed motility
Describe the difference in the sperm’s swimming pattern in the male v. in the female.
male: elegant swimming w/ equal peaks & valleys
female: goes crazy! more forceful, can penetrate mucus & make it to the secondary oocyte
T/F The sperm are more motile in the male right before ejaculation than in the female.
False.
there is an initial ejaculation motility
then there is hyper activated motility in the female.
What is better for a sperm to swim in: neutral/alkaline environment or acidic environment?
Alkaline environment, greater motility
How long can the sperm typically survive in the female reproductive tract?
1-2 days
What is the function of the seminal vesicles?
secrete mucus that empties into the ejaculatory duct...rich in: fructose (nutrition for the sperm) citric acid prostaglandins (aid fertilization) fibrinogen
How does female orgasm help w/ fertilization?
it causes contraction & prostaglandin release…negative pressure that sucks sperm in
How does the prostate gland add fluid to the semen?
during emission it contracts w/ the vas deferens
What is roughly the pH of the prostate gland secretions? Why is this important?
They are roughly acidic, this is to neutralize the basic secretions of the seminal vesicles
What types of substances are contained in the prostate gland secretions?
calcium
citrate ion
clotting enzyme
profibrinolysin
What are the 4 sources that contribute to semen fluid? What percentage does each contribute?
vas deferens (10%) seminal vesicles (60%) prostate gland (30%) bulbourethral glands (small amt)
How long can sperm last if they are properly preserved?
years via cryopreservation
What is the pH of semen fluid?
pH=7.2-8
What is the appearance of semen?
milky appearance
coagulum that dissolves in 15-30 minutes
What is the coagulum in the semen? Why does it dissolve after 30 minutes?
coagulum–clotting enzyme
dissolves b/c of fibrinolysin in the semen derived from profibrinolysin
What does capacitation of sperm do? How can you capacitate sperm?
it makes the sperm capable of fertilizing an egg
- *occurs naturally in the female genital tract w/i 1-10 hours
- *can artificially do it by washing the sperm in human tubular fluid or a capacitation medium
What changes occur to the sperm during capacitation?
- *inhibitory factors that suppress sperm activity are washed off…
- *lipid vesicles are removed from the acrosome & the acrosomal enzymes are released
- *sperm membrane becomes permeable to calcium–>hyperactivates motility–>ability to penetrate ZP
The acrosome is essential for the sperm to be able to fertilize the egg. What is it derived from? What does it contain?
- *Derived from Golgi apparatus during spermiogenesis
- *hyaluronidase: to get thru CT layers & the granulosa cells
- *proteases: to get thru the ZP
What are 2 reflexes that have to do w/ the scrotum?
reflex regulation of scrotal surface area
reflex regulation of distance from abdomen
Aside from being outside of the body, what is another way that the scrotum is kept cool?
countercurrent heat exchange
T/F There are NOT sweat glands in the scrotum.
False. There are.
What is cryptorchidism?
- *this is a cause of male infertility
- *the testes don’t descend even 3 months after birth as they should in response to fetal Leydig cells’ release of testosterone
- *can cause spermatogenic block w/ testes in abdomen, depletion of germ cells, sterility, & tumor formation.
What is the treatment for cryptorchidism?
testosterone administration
after 1 year if they still haven’t descended–>surgical intervention.
T/F Globally, sperm count is getting lower & lower.
True. Now, a normal sperm count is 10 million per mL.
What is a sperm count that is considered infertile?
What is considered normal?
Normal: 25-200 million sperm/mL
Infertile: less than 20 million sperm/mL
What are impulses from the brain for the male sexual act?
psychic stimulation from thinking or dreaming (nocturnal emissions)
What are the impulses from the sex organs for the male sexual act?
glans penis or areas adjacent to the penis
Where are the brain & sex organ impulses integrated w/ the male sexual act?
sacral & lumbar spinal cord
How do the impulses from the male sex organs travel to the sacral & lumbar spinal cord?
Impulses–>pudendal nerve–>sacral plexus–>sacral portion of the spinal cord
Penile Erection:
What is the path of parasympathetic impulses to the penis? Which substances are released to make this happen?
Parasympathetic Impulses–>Sacral portion of the spinal cord–>pelvic nerves–>penis
**Releases: NO, Vasoactive Intestinal Peptide, ACh
What is the function of NO in a penile erection?
- *relaxes penile arteries
- *relaxes trabecular meshwork of smooth muscle fibers in erectile tissue of corpus cavernosum & corpus spongiosum in the penis
How does lubrication happen as a part of the male sexual act?
parasympathetic response
secretion of mucus from urethral glands & bulbourethral glands!
Emission & ejaculation are both _____ responses. Describe the reflex that makes emission happen.
sympathetic responses
reflex center @ T12-L2 of spinal cord–>sympathetic impulses–>hypogastric & pelvic sympathetic nerve plexuses–>genital organs–>emission.
Describe the contraction part of ejaculation.
Vas Deferens–>expulsion of sperm into internal urethra
prostatic & seminal fluids get into urethra
mucus from bulbourethral & urethral glands contributes
What happens when the internal urethra is filled?
sensory signals are given off…causes rhythmic contractions of the internal genital organs & pelvic muscles; causes thrusting of the pelvis & penis & propulsion of the sperm.
When does resolution of the male sexual act happen?
1-2 minutes after ejaculation
What percentage of testosterone in the man comes from the adrenal glands?
5% of testosterone comes from the adrenal glands.
What percentage of testosterone is found in the blood? When it is in the blood–>which carrier proteins is it bound to?
5% of testosterone is found in the blood
carried on ABP (from Sertoli cells)
albumin
What is testosterone converted to in the liver? in target tissues? How?
Liver: converted to DHT by 5 alpha reductase Type I.
Target tissues: converted to DHT by 5 alpha reductase Type II.