reproduction - 1 men Flashcards
what is the role of the seminiferous tubules
produce spern
when does spermatogenesis begin
puberty
what is the role of leydig cells
secrete testosterone
what is the role of sertoli cells
support sperm development
what are myoid cells
smooth muscles that do peristalsis to propel sperm
what is the blood testis barrier
tight junctions between the luminal and basal compartment
which cells are the epithelial cells
sertoli cells
which cells are the interstitial cells
leydig cells
what is the trophic role of sertoli cells
support sperm development
what do sertoli cells secrete (3)
- luminal fluid for sperm housing
- androgen binding protein
- inhibin
what do androgen binding proteins do (2)
buffer androgens and help maintain steady [androgens] in lumen
which hormones are sertoli cells a target for
testosterone and FSH
what is inhibin
hormone of negative feedback loop for FSH
who secretes inhibin
sertoli cells
where is old and damaged sperm phagocytized
sertoli cells
where is the site of immunosupression
sertoli cells (blood testis barrier)
what are 2 roles of the gonads
production of sperms and hormones
what is the role of the scrotum
temperature regulation
what are 2 roles of the epididymis
maturation of sperm
storage site for sperm
what are 2 roles of the vas deferens
channel
storage site for sperm
what is the role of the accessory sex glands
production of seminal fluid
what is the precursor for steroid hormones
cholesterol
is progesterone found in males or females
both
are corticosteroids slow or fast acting
slow
which cells are under influence of LH
leydig cells
what causes the descent of the testes
high levels of testosterone
when do the testes descent
7 months (before birth)
is testosterone or adrenal androgens more potent
testosterone
what are 4 fates of testosterone
-stays as T
-becomes E
becomes inactive
-becomes DHT
what does DHT do
helps with maintaing healthy prostate gland
how potent is DHT
very
what stage in life are men able to reproduce
puberty
how many peaks of testosterone through a mens life & when
- 2nd trimester
- neonatal (differentiation)
- puberty (descends till death)
where is GnRH released from
hypothalamus
where does GnRH act
anterior pituitary
where is LH produced
anterior pituitary
what causes LH production
GnRH acting at the anterior pituitary
what causes FSH production
GnRH acting at the anterior pituitary
where is FSH produced
anterior pituitary
where does LH act
leydig cells
where does FSH act
sertoli cells
what happens when LH activates leydig cells
testosterone is released
what causes 2ary male sexual characteristics
testosterone release from leydig cells
where can testosterone negative feedback
on anterior pituitary (desensitive to GnRH) and hypothalamus
what was the patten of GnRH release before puberty
slow and steady release
what was the patten of GnRH release in puberty
major pulses with higher amplitude and frequency
what is an anabolic effect of androgens
promote protein synthesis in skeletal muscles
what do androgens do to spermatogenesis
stimulate
what do androgens do to 2ary characteristics
promote
what do androgens do to sex drive
increase
what do androgens do to growth hormone secretion
increase
what do androgens do to erythropoietin
testosterone increases it (men have more RBC than women)
where does spermatogenesis occur
seminiferous tubule
how long does it take from meiosis 1 until you have spermatozoa
64 days
what is the purpose of mitosis in spermatogenesis
ensures continous supply of spermatogonia
what are spermatogonia
the ones going through mitosis and differentiation
what happens to chromosome number in meiosis in spermatogenesis
chromosome number becomes half
what is differentiation and packaging in spermatogenesis
specialization for transport and delivery of proper genetic material
where does spermatogenesis start (where are spermatogonia)
in the basement membrane
which direction does spermatogenesis continue
towards the lumen
where does spermatogenesis happen (specific)
between the space between adjacent sertoli cells
what is spermiogenesis
how spermatid develop into a complete spermatozooa
what is the difference with spermatogenesis and spermiogenesis
spermiogenesis is the last step of spermatogenesis
how long does spermiogenesis take
24 days
what happens in spermiogenesis
structural changes, it sheds cytoplasm, gets tail, makes a mitochondrial spiral
what are the three structures in the sperm
head
midpiece
tail
what is in the head of the sperm
nucleus and chromosomes
acrosome
what are acrosomes
enzymes that are necessary for fertilization
what is in the midpiece of the sperm
mitochrondia - energy source
what is in the tail of the sperm
what makes the wavelike(not mature) and whiplike(fully mature) movements
what is the name of the sperm after spermiogenesis
spermatozoa
what happens to the spermatozoa after they are made
they are released into the lumen of seminiferous tubules and stay immotile for 20 days
what causes the sperm to move to the epididymis
pressure generated by the fluid secreted from sertoli cells
how long do sperm stay in the epididymis
6-12 days
what happens to sperm in the epididymis (2)
aquire wave-like movement/motility
-fluid is reabsorbed to concentrate sperm
how do sperm move into vas deferens
peristalsis
what does FSH do
stimulates gametogenesis
what does LH do
stimulates androgen secretion
who creates the pulse generation of GnRH
the hypothalamus
where does GnRH act
anterior pituitary
what two hormones are released from the anterior pituitary in response to GnRH
LH and FSH
how do sertoli cells do negative feedback
release inhibin onto the anterior pituitary
can inhibin act on the hypothalamus
no
can testosterone act on the hypothalamus
Yes
how do leydig cells do negative feedback
release testosterone which acts on the anterior pituitary and the hypothalamus
what is the frequency of pulses of GnRH in men
90 mins
does testosterone act on sertoli cells
yes and it causes a secretion of paracrine factors that stimulate spermatogenesis
what happens when testosterone and FSH act on sertoli cells
they secrete paracrine factors that stimulate spermatogenesis
what kind of a hormone is FSH LH and TSH
glycoproteins
how does the prostate gland release its secretions
it has tiny holes that gives out its secretion
what are the 3 functions of seminal fluid
dilution of sperm
fructose for energy
make semen clot
what % of semen volume is seminal fluid
60%
what makes the semen clot
semenogelin is a protein
what is the point of a semen clot
to help deposit semen into the female tract
sperm + seminal fluid = ?
semen
what do the seminal vesicles secrete
alkaline fluid witth fructose, enzymes and prostaglandins
what do the prostaglandins from the seminal vesicle cause
they stimulate uterine contractions
what does the prostate gland secrete
citrate and enzymes (PSA)
what is PSA
prostate specific androgen - antioxidant to help sperm survive and to dissolve the clot so sperm can swim away freeeeely
where is PSA released from
prostate gland
what does high levels of PSA mean
either prostate cancer or a benign growth
what do the bulbourethral glands secrete
viscous fluid with mucus
what nervous system does erection
parasympathetic
what nervous system does emission
sympathetic nervous system
how does the nervous system do emission
sympathetic stimulation to the smooth muscles of the ducts
what kind of nervous system is involved in ejaculation
somatic nervous system control
what happens after the parasympathetic nerve is activated (erection pathway)
increased nitric oxide
what happens after nitrric oxide in increased
increase cGMP
where does nitric oxide and cGMP act
on smooth muscle
what happens with increased cGMP
vasodilation, increased blood flow and erection
how is cGMP broken down
by phosphodiesterase
what does cGMP break down into
inactive product (doesnt make erection)
what does sildenafil do
it inhibits phosphodiesterase so then cGMP remains to keep erection
what causes erections to stop in men (unwanted)
cGMP is broken down by phosphodiesterase
what accounts for the low number of sperm to reach the site of fertilization
high acidity and not all of them have enough energy
what is capacitation
changes in sperm head and tail
why must sperm go through capacitation
sperm must go through this to be able to fertilize
what happens to the head in capacitation
destabilization of sperm surface membrane
what happens to the tail in capacitation
wavelength movement becomes a whiplike movement
when does the acrosome reaction happen
after capacitation
what happens in the acrosome reaction
the membrane opens up and releases the acrosomal enzymes
how many sperm are produced per day
30 000 000 sperm/day
which hormone works on the male internal genitalia before birth
testosterone
which hormone works on the male external genitalia before birth
DHT
