Male Physiology Flashcards
why is male physiology important to dentistry?
hormones impact:
salivary flow
bone loss
tooth loss
diseases
SjD (inflammation in salivary glands)
what is the relationship between male testosterone levels and Sjögren’s disease?
they are inversely related
SjD = decreased testosterone
Male reproductive organs have a dual function (2)
- Production/Transmission of germ cells (gametogenesis)
- Secretion of sex hormones
Testes secrete a large amount of ______ and small amounts of _____
androgens (testosterone)
estrogen
Male gonadotropic secretion occurs in a __-____ fashion with a slow
decrease with aging
non-cyclic
males maintain the ability to produce ___ ____ as they age
viable gametes
*ability to fertilize last longer with age
how many seminiferous
tubules per testis?
200-400 per testis
Spermatozoa are formed in the ___ of
seminiferous tubules from the primitive germ cells
walls
Spermatozoa are formed in the walls of
seminiferous tubules from the __ ___ cells
primitive germ cells
spermatogenesis
Spermatozoa are formed in the walls of
seminiferous tubules from the primitive germ cells
male physiology: Both ends of each loop drain into a network of ducts in the head of the ____
epididymis
after drainage into the epididymis where do the spermatozoa go?
spermatozoa pass through the tail of the epididymis into the vas deferens
Both ends of each loop drain into a network of ducts in the head of the epididymis. From there, spermatozoa pass through the tail of the epididymis into the __ ___
vas deferens
after spermatozoa enter the vas deferens, they enter through the ___ ____ into the urethra
ejaculatory ducts
spermatozoa enter through the ejaculatory ducts into the urethra in the body of the _____ at the time of ejaculation
prostate
Seminiferous Tubules
Tubules where spermatogenesis occurs
septa
Fibrous tissue that subdivides the testis into ~250 lobules
Tunica Albuginea
fibromuscular connective tissue capsule of the testis
Rete Testis
tubules located in the hilum of the testicle that carries sperm from the seminiferous tubules to the efferent ducts
epididymis
highly coiled, single tube that is a storage reservoir for spermatozoa
Vas Deferens
duct that transports sperm between the epididymis and the ejaculatory duct in anticipation of ejaculation
Between the tubules in the testes are nests of ___ ___
Leydig cells
Leydig cells
Secrete testosterone into the bloodstream
Blood spermatic arteries runs _____ but in the ______ direction to blood in the
spermatic veins
parallel
opposite
Blood spermatic arteries run parallel and opposite direction to blood in the
spermatic veins which allows for …
countercurrent exchange of heat
and testosterone
The composition of the fluid in the
seminiferous tubules is different from
plasma in what ways?
low protein and glucose
high in androgens, estrogens, K+, inositol, and glutamic and aspartic acids.
Maintenance of its composition depends on the blood testis barrier.
Blood-Testis barrier formed by tight
junctions of what cells?
Sertoli Cells
Blood-Testis barrier protects germ cells from:
Bloodborne pathogens/toxic agents
Blocks antigenic products of germ cell division from entering the circulation and generating an autoantibody response
Help establish an osmotic gradient that
facilitates the movement of fluid into the tubular lumen
what issues with male reproductive
system post SARS infection has been noticed?
Increased IgG in seminal fluid (change morphology and increased apoptosis)
The walls of the seminiferous tubules
are lined by what? (2)
primitive germ cells and Sertoli cells
Germ cells must stay in contact with
Sertoli cells to survive via ?
thru cytoplasmic bridges (CB)
Germ cells must stay in contact with
___ to survive; thru cytoplasmic
bridges (CB)
Sertoli cells
Cytoplasmic Bridge functions (3)
- Tight junctions form a blood-testis
barrier - Passing macromolecules between cells
- Enables synchronous cell development
As cells (sertoli cells/primitive germ cells) mature, they pass from ____ to the ____
basal lamina region to the lumen
how do the mature cells in the blood-testis barrier move from the basal lamina region to the lumen?
Occurs by the coordinated breakdown of the tight junctions above the germ cells and the formation of new tight junctions below them
What do the primitive germ cells of the seminiferous tubules mature into?
primary spermatocytes
the maturing of the spermatogonia (primitive germ cells) into the primary spermatocytes occurs when?
during adolescence
Each sperm is an intricate motile cell, rich in DNA, with a head that is made up mostly of ____ material
chromosomal
Each sperm is an intricate motile cell, rich in ___, with a head that is
made up mostly of chromosomal material
DNA
Acrosome
Head of sperm
(lysosome-like organelle rich in enzymes involved in sperm penetration of the ovum and other events associated with fertilization)
the tail of sperm is wrapped in its proximal portion by a sheath holding many ___
mitochondria
structure of sperm
head (acrosome - DNA rich)
tail (mitochondria)
The ability of sperm to move forward is called
progressive motility
*acquired in the epididymis
Spermatozoa leaving the testes are not fully ___
mobile
sperm continue their maturation and acquire motility during their passage through the ___
epididymis
sperm progressive motility involves the activation of cation channel proteins from the ___
CatSper family
Once ejaculated into the female, the spermatozoa move up the uterus to the
uterine tubes, where they slow down and undergo ____
capacitation
This further maturation process involves what two components?
increasing the motility of the spermatozoa
facilitating their preparation for the acrosome reaction
Spermatogenesis requires a temperature considerably___ than that of the interior of the body
lower
(about 32°C)
how do the testis stay cool?
air circulating around the scrotum
heat exchange in a countercurrent manner between the spermatic arteries
and veins
the fluid that is ejected during orgasm contains what? (5)
sperm
secretions of seminal vesicles
secretions of prostate
secretions of Cowper glands
secretions of the urethral gland
each milliliter of semen normally contains about ___ sperm
100 million
what levels of sperm/ml are standard, reduced, and sterile?
Standard: 100 million sperm/ml
Reduced: 20-40 million sperm/ml
Sterile: <20 million sperm/ml
composition of sperm
sperm
from seminal vesicles (60%)
from prostate (20%)
buffers (Ph and bicarbonate)
> 50% decrease in sperm count since when?
~1970s
Within the next 20-40 yrs, sperm counts
may be less than ____ sperm/ml
20 million
male contreceptions (4)
hormonal control of sperm development
targeting of cation channel proteins
important in fertilization [e.g., CatSpers]
natural compounds
that limit sperm function
vasectomy
The prostate produces and secretes into the semen/bloodstream a 30-kDa serine protease generally called
prostate-specific antigen (PSA)
The gene for prostate-specific antigen (PSA) has two ____ response elements
androgen
PSA hydrolyzes the sperm motility inhibitor ____ in semen
semenogelin
An elevated plasma PSA occurs in (3)
prostate cancer
prostatic hyperplasia
prostatitis
*widely used as a screening test for prostate cancer
Testosterone is a
C__ steroid with a ____
group in the __th position
C19 steroid with a hydroxyl
group in the 17 position
testosterone is synthesized from what?
cholesterol (in the Leydig cells)
testosterone is synthesized from
cholesterol in the Leydig cells and is also formed from ____
secreted by the adrenal cortex
androstenedione
Secretion of testosterone by Leydig cells is under the control of ___
luteinizing
hormone (LH)
testosterone in plasma is bound to proteins (3)
gonadal steroid–binding globulin (GBG)
or
sex steroid–binding globulin
albumin (33%)
Circulating testosterone is converted to
17- ketosteroids (majority - androsterone)
estradiol (small amount)
Testosterone and other androgens exert an inhibitory feedback effect on pituitary __ secretion
LH
testosterone anabolic effects (3)
Increase synthesis proteins (increased rate of growth)
increase the size of kidneys
retention of Na+, K+, H2O, Ca2+, SO42−, and PO43−
mechanism of action of testosterone
Testosterone and other androgens (DHT) bind to hormone responsive elements (HRE). Activation of HRE triggers nuclear localization and binding (as dimer) to DNA and facilitates transcription of genes.
Congenital 5α-Reductase Deficiency
Produces pseudohermaphroditism.
*Individuals are born with male internal
genitalia including testes, but they have
female external genitalia (increased testosterone)
Klinefelter’s Syndrome:
XXY, 47
X and Y chromosomes
long legs
cognition deviations
Cryptorchidism
one or both testes fail to descend from the abdomen
Gonadotropic hormone treatment speeds descent
*too warm for testis (infertility)
Male Hypogonadism
decreased testosterone
decreased circulating gonadotropin levels
spermatogonium (stem cells) transition to spermatids take approx how long?
74 days
t/f: cytoplasmic bridges are what maintain tight junctions in seminiferous tubules
true
a condition where testes do not descend?
cryptorchidism
t/f: testosterone released from Leydig cells increased LH secretion
false
a majority of testosterone is converted to what before being excreted in urine?
androsterone
etiocholanolone
t/f: CatSper cation channels regulate sperm mobility
true
what part of the sperm contains concentrated mitochondria?
middle piece (proximal portion of tail)
T/F: Klinefelter’s syndrome is characterized by 2 X chromosomes and 1 Y chromosome (XXY, 47)
true
T/F: elevated PSA is only indicative of prostate cancer
false
prostate cancer
prostatic hyperplasia
prostatitis
vasectomy is performed by ligating what?
vas deferens
