Lecture 23 -- review questions Flashcards
what organs produce the gametes in the male?
are they primary or secondary sex organs?
why?
primary sex organs
testes
primary sex organs == gonads == the organs that produce the gametes –> sperm
is the penis a primary or a secondary sex organ? why?
secondary sex organs
organs other than gonads that are necessary for reproduction
penis doesn’t produce gametes but is still necessary for reproduction == secondary sex organ
what are the male gametes called?
sperm
what is the scrotum?
a pendulous pouch of skin, muscle, and fibrous connective tissue
contains the testes
where is the scrotum?
hangs below the penis
which organ does the scrotum contain?
testes
what is the purpose of the scrotum?
hold the testes
provide a temp slightly lower than that of body temp, as required to produce viable sperm
what would happen if the testes were located inside the body?
it would be the same temp as the body –> too hot –> sperm would no longer be viable
are testicles the same as testes? and testis?
testicles == testes
one testicle == testis
what is the temperature in the human testis? and in the body?
temp in human testis ==> 32-35 C
temp in body ==> ~37 C
where is the dartos muscle located?
surrounds the testes subcutaneously (underneath)
where is the cremaster muscle located?
surrounds the testes (covers them)
which muscle produces the wrinkles of the scrotum?
how?
dartos muscle
when cold
==> dartos muscle contracts
==> decrease surface area to reduce heat loss
==> gives skin a wrinkled texture
which muscle contains skeletal fibers: dartos or cremaster muscle?
cremaster muscle
which muscle lowers and raises the testis in order to control its temperature?
cremaster muscle
what happens to the scrotum if you apply ice there?
how about the testicles? do they change their position? if so, how?
dartos muscle will contract –> scrotum becomes taut and even more wrinkled –> decreases SA to reduce heat loss
cremaster muscle will contract –> raise testes and draw them closer to body to preserve heat
how do dartos and cremaster muscles respond when the environment is freezing?
dartos muscle will contract –> scrotum becomes taut and more wrinkled –> decreases SA of scrotum to reduce heat loss
cremaster muscle will contract –> raise testes and draw them closer to body to preserve heat
how do dartos and cremaster muscle respond when the environment is really hot?
dartos muscle will relax –> scrotum becomes looser and less wrinkled –> increases SA of scrotum to increase heat loss
cremaster muscle will relax –> lower testis and suspend them farther from the body to lose more heat
what is the pampiniform plexus made of, veins or arteries?
where is it located?
veins
located above the testicles
what structure acts as a countercurrent heat exchange to control the temp of the artery supplying blood to the testicles?
pampiniform plexus
how does the artery supplying blood to the testicles get rid of heat to decrease its temperature before entering the testicles?
some heat from descending artery gets transferred over to ascending veins of the pampiniform plexus
what would happen if the blood reaching the testes was at the same temperature as the rest of the body (37 C)?
the blood would heat the testis and inhibit sperm production
are the veins leaving the testicles cooler or warmer than the rest of your body?
cooler
what is the direction of heat transferring b/n the artery and veins in this mechanism for cooling down the temp in the testicles?
(from the artery to the veins or vice versa?)
from artery to veins
what are the seminiferous tubules?
tubules that make up the testes
has a narrow lumen lined by a thick germinal epithelium
where spermatogenesis takes place
where does spermatogenesis take place?
seminiferous tubules
are Leydig cells inside or outside of the seminiferous tubules?
outside
what hormone do Leydig cells produce?
testosterone
what is the name of the cells surrounding the seminiferous tubules?
peritubular myoid cell
what are other names for Sertoli cells?
sustentocytes
“nurse” cells
where are the Sertoli cells?
spans the entire seminiferous epithelium
what are the 3 main functions of the Sertoli cells?
(1) nourish developing sperm cells thru the stages of spermatogenesis
(2) secretes 2 proteins that regulate sperm production: androgen-binding protein (ABP) and inhibin
(3) secretes fluid for sperm transport
what other cells can you see b/n the Sertoli cells inside the seminiferous tubules?
mitotic germ cells
meiotic germ cells
spermatozoa
what is spermatogenesis?
the sequence of events that leads to formation of sperm (male gametes) in the seminiferous tubules
what hypothalamic hormone stimulates the release of FSH and LH from the anterior pituitary gland? (full name)
GnRH
gonadotropin-releasing hormone
what do FSH and LH stand for?
FSH == follicular stimulating hormone
LH == luteinizing hormone
what cells do FSH and LH act on?
what happens upon stimulation of these cells by these hormones?
FSH –> Sertoli cell –> release inhibin and androgen-binding protein (ABP) –> leads to spermatogenesis
LH –> Leydig cell –> release testosterone –> binds to androgen-binding protein –> leads to spermatogenesis
what is inhibin? (source of production, action)
hormone that gets released when FSH acts on Sertoli cell
inhibits the synthesis and release of FSH and reduces LH
what protein does testosterone bind to in order to stimulate spermatogenesis?
androgen-binding protein (ABP)
will high testosterone levels stimulate or inhibit the release of LH/FSH?
inhibit
negative feedback effect
high testosterone –> inhibits hypothalamus – no GnRH release –> anterior pituitary gland – no FSH or LH
in spermatogenesis, what of the following cells act as stem cells: spermatogonia, spermatocyte, spermatid, spermatozoon?
spermatogonia
(from primordial germ cells)
what is the singular noun for spermatogonia?
spermatogonium
what is the difference b/n haploid and diploid?
haploid – single set of chromosomes
- daughter cells with 23 unpaired chromosomes
diploid – 2 sets of chromosomes, one from each parent
- parent cells with 46 chromosomes in 23 homologous pairs
which cells are diploid:
spermatogonia type A,
spermatogonia type B,
primary spermatocyte,
secondary spermatocyte,
spermatid,
spermatozoa?
spermatogonia type A
spermatogonia type B
primary spermatocyte
which cells are haploid:
spermatogonia type A,
spermatogonia type B,
primary spermatocyte,
secondary spermatocyte,
spermatid,
spermatozoa?
secondary spermatocyte
spermatid
spermatozoa
what type of cell division (mitosis or meiosis) do spermatogonia type A go thru to maintain the stem cell pool?
mitosis
one daughter cell from each division remains near the tubule wall as stem cell (type A)
the other daughter cell (type B) migrates slightly away and enlarges and becomes a primary spermatocyte
what type of cell division (mitosis or meiosis) does the primary spermatocyte undergo to be converted into a secondary spermatocyte?
meiosis I
gives rise to 2 equal-size, haploid, secondary spermatocytes
after the secondary spermatocyte goes thru meiosis II, what is the name of the resulting cells?
do they contain the exact number of chromosomes as the secondary spermatocyte?
and as the primary spermatocyte?
spermatides
same # of chromosomes as secondary spermatocyte (23)
half the number of primary spermatocyte (46)
what is the plural noun for spermatozoon?
spermatozoa
which of the different cells that are part of the spermatogenesis process are closest to the lumen of the seminiferous tubules?
and on the periphery, closest to the peritubular myoid cells?
which of those cells is known as “sperm cell”?
spermatozoa closest to lumen
spermatogonia closest to peritubular myoid cells (outside of seminiferous tubule)
spermatozoa = sperm cell
place in order, from the first to the last, in being created:
spermatogonia type A
secondary spermatocyte
spermatozoon
spermatogonia type B
primary spermatocyte
spermatid
spermatogonia type A
spermatogonia type B
primary spermatocyte
secondary spermatocyte
spermatid
spermatozoon
what is spermiogenesis?
differentiation of the spermatids into spermatozoa
have the testicular spermatozoa acquired the ability to move progressively and fertilize oocytes?
no
must become fertilization-competent first by going thru biochemical changes –> epididymal maturation process in the male and capacitation in the female tract
which 2 other processes must the testicular spermatozoa go thru to become fertilization-competent? where?
biochemical changes
epididymal maturation process –> male
capacitation –> female tract
in the process of transformation from spermatids to spermatozoa, what happens with the overall shape of the cell?
sprouts a tail (flagellum) and discards most of its cytoplasm
develops a midpiece that contains the mitrochrondria and an acrosome head
what is the acrosome? where is it?
lysosome that contains enzymes used to penetrate the egg
located in the head
what are the 3 parts of the spermatozoon’s tail?
middle piece (top of tail)
principal piece of tail (middle of tail)
endpiece of tail (bottom of tail)
in the spermatozoon, where are the mitochondria located, in the head or in the tail?
tail (middle piece)
what is the axoneme?
tail of tubulin
located in middle piece of tail
why does the spermatozoon need ATP?
to allow sperm to beat their tails as they migrate up the female reproductive tract
what are the 3 erectile tissues? where are they? which of these 3 cylindrical bodies surrounds the urethra?
corpora cavernosa (2)
corus spongiosum (1)
found at shaft of penis
corpus spongiosum surrounds the urethra
what can you find inside the corpora cavernosa?
sinusoid cavities
cavernosal smooth muscle cells
endothelial cells
what is the physiological definition of erection?
engorgement of the erectile tissue w/ blood –> causing the penis to become rigid == erection
which nervous system division controls erection? how?
parasympathetic NS
–> increases secretion of nitric oxide (NO)
–> relaxes smooth muscle cells
–> allows the sinusoids (in the corpora cavernosa) to dilate and fill with blood
what does vasocongestion mean?
swelling of genitals with blood
are other sex organs larger during erection?
yes
testes
corpus spongiosum
when the parasympathetic NS is stimulated, what is the effect on the arteries supplying blood to the penis, Vd or Vc?
vasodilate
what molecule activates guanylyl cyclase?
nitric oxide (NO)
what is the function of guanylyl cyclase?
produce cGMP
what is the function of cGMP in the smooth muscle of the corpus cavernous?
(ion, effect on muscle contraction or relaxation, blood coming in or out)
decreases amount of Ca2+ within the corpus cavernosum (decreased intracellular concentration)
relaxes smooth muscle of the deep arteries and cavernous spaces of the corpora cavernosa
–> increase blood flow into erectile tissues to bring an erection
which enzyme degrades cGMP? (full name)
PDE5
phosphodiesterase type 5
what prostaglandin has receptors in the smooth muscle of the corpus cavernosum?
upon stimulation of prostaglandin receptors, it will activate which enzyme?
PGE1
adenylyl cyclase (converts ATP to cAMP)
what is the function of cAMP in the smooth muscle of the corpus cavernosum?
(ion, effect on muscle contraction or relaxation, blood coming in or out)
produces AMP
lowers Ca2+ concentration in smooth muscle of corpora cavernosa
–> smooth muscle of corpora cavernosa relaxes
–> blood comes in to erectile tissue –> erection
what is ejaculation?
propulsion of semen from the male duct system
promoted by the sympathetic NS
entire ejaculatory event == climax or orgasm
which autonomic NS division controls ejaculation?
sympathetic NS
where does sperm go after seminiferous tubules?
(1) seminiferous tubules
(2) rete testis (where they partially mature)
(3) efferent tubules
(4) epididymis (finish maturing and are stored)
(5) vas deferens (ductus deferens) –> propels the sperm thru the ejaculatory ducts into the urethra by peristalsis during ejaculation
what is the pathway of sperm in order?
(starting at the seminiferous tubules, 7 structures in total)
(1) seminiferous tubules
(2) rete testis
(3) efferent tubules
(4) epididymis head
(5) vas deferens AKA ductus deferens
(6) ejaculatory ducts
(7) urethra
once the sperm is created, will it remain in the testicles waiting for ejaculation?
yes; will stay in testicles
created in seminiferous tubules
partially mature in rete testis
finish maturing and are stored in the epididymis head
where is sperm stored before ejaculation, and for how long?
stored in epididymis head
stored for 40-60 days
where do sperm mature and develop their ability to move or swim?
epididymis head
what are the 3 parts of the epididymis?
head, body, tail
tail is bottommost
head is topmost
what is the rete testis?
part of testes
sperm go from (1) seminiferous tubules to (2) rete testis
where sperm partially mature
sperm go from (2) rete testis to (3) efferent tubules
tubules to help sperm move from seminiferous tubules to epididymis
what 2 ducts form the ejaculatory duct?
vas deferens (ductus deferens)
duct of the seminal vesicle/gland
what is semen?
seminal fluid
fluid expelled during orgasm –> an alkaline fluid that dilutes and transports sperm
how do sperms get nutrients (to product ATP)?
fructose and citrate from seminal vesicles
citrate from prostate gland
what are the glands that contribute to the composition of semen?
seminal vesicle/gland = 65-75%
prostate gland = 20-30%
bulbourethral/Cowper’s gland = 1%
which gland contributes the most significant volume to semen?
seminal vesicles == 65-75%
what is the role of fructose and citrate in the semen?
what organs secrete them?
provide nutrients for sperm
seminal vesicles secrete fructose and citrate
prostate gland secretes citrate only
what are 2 functions of the prostaglandins secreted by the seminal vesicle into the semen?
(1) stimulate peristalsis of ductus deferens and uterus
(2) inhibit sperm rejection by female immune system
what are 2 functions of the calcium ions secreted by the seminal vesicle into the semen?
stimulate sperm motility
stimulate enzymes release from acrosome for egg penetration
what gland produces semenogelin?
seminal veiscles
is prosemenogelin active in the seminal vesicles?
which enzyme activates it?
where does this enzyme come from?
no; inactive in seminal vesicles
clotting enzyme produced by prostate gland activates prosemenogelin
- prosemenogelin –> semenogelin
clotting enzyme comes from prostate gland
what does PSA stand for?
prostate-specific angigen
what is PSA?
breaks down semenogelin
liquifies coagulated semen after delay
is PSA active in the prostate gland? why?
no; because it is inhibited by zinc in the prostate gland
after ejacuation –> semenogelins bind to a lot of free zinc –> less zinc bound to PSA –> PSA is activated
what is another name for bulbourethral gland?
Cowper’s gland
what do the bulbourethral glands secrete?
preejaculate
a clear slippery alkaline fluid (mucus + buffers) that lubricate the head of the penis in preparation for intercourse
what is the role of the buffer secreted by the bulbourethral glands?
protects the sperm by neutralizing the acidity of the male’s urethra and female’s vagina
when the semen is ejaculated, why is it liquid?
prosemenogelin (from seminal vesicle) and clotting enzyme (from prostate) are stored separately –> don’t mix together until during ejaculation
after prosemenogelin gets activated by clotting enzyme –> becomes semenogelin –> coagulation
what is released from the prostate that breaks down semenogelin?
PSA (prostate-specific angigen)
PSA breaks down semenogelin and liquifies the semen
why does the semen coagulate after being ejaculated? how?
prosemenogelin mixes with clotting enzyme –> activates semenogelin –> coagulates the semen
what happens to the PSA when semenogelin binds zinc ions?
yes it become active or inactive?
PSA becomes active
how does semen liquefy again?
what is the role of PSA in this process?
semenogelin causes clotting
PSA breaks down semenogelin and liquifies semen
what is the name of the sensory nerve that innervates the penis and transmits signals to the spinal cord’s erection-generating center?
pudendal nerve
where is the erection-generating center located?
sacral segments
which autonomic NS generates a response to the physical stimulation of the penis?
parasympathetic NS
physical stimulation of penis
–> sensory signals from pudendal nerve to spinal erection center
–> erection-generating center located in sacral segments
–> interneurons stimulate nearby parasympathetic neurons
–> transmit erection-inducing signals from the sacral spine to the penile blood vessels
why does the sympathetic NS constrict the bladder’s internal sphincter during ejaculation?
to prevent expulsion of urine or reflux of semen into the bladder
what are the actions of the sympathetic NS on the reproductive ducts and accessory glands during ejaculation?
stimulates reproductive ducts and accessory glands to contract –> empty contents into urethra
what is the factor that triggers the expulsion of semen by the penis?
what NS controls that?
what is the muscle responsible for that?
semen in the urethral triggers a spinal reflex –> undergoes 5-6 strong, spasmodic contractions that compress the urethra and forcibly expel the semen
motor (somatic) NS
bulbospongiosus muscles
where is the bulbospongiosus muscle located?
envelopes the root of the penis
what structure does the bulbospongiosus muscle compress when contracted?
urethra
compression of urethra helps to forcibly expel the semen
