Download Male Reproductive System

Male Reproductive System
I Can describe the structure and
function of the male reproductive
system including the following:
•
•
•
•
•
•
•
•
•
•
•
Testes
Seminiferous tubules
Interstitial cells
Epididymis
Vas deferens,
Cowper`s gland
Seminal vessicles
Prostate gland
Ejaculatory duct
Urethra
Penis
Review of Sexual Reproduction
• Both parents donate ________ material
• Offspring will be different than parents and
each other
• More _________ in sexual reproduction than
asexual
– A parent cell divides to create two cells that are
identical to one another and parent
Male Anatomy
• Male and female sex organs originate in the
__________ cavity
• During the ________ month the genes of the
sex chromosomes cause differentiation
• Testes descend through a canal in the scrotum
Urinary Bladder
•
• Sphincter regulates the
voiding of fluid from the
bladder
Ureter
• Carries ______ from the ________ to the
urinary bladder
Scrotum
• Pouch of skin below the pelvis that contains the
______
• Keeps testicles ______ to allow ________ of
sperm
• Descend through small canal from abdominal
cavity to scrotum during the last two months in
utero
• Membrane of skin forms over canal preventing
testes from re-entering abdominal cavity
Scrotal Abnormalities
• Deformities:
– ___________________
• Testes fail to drop from body cavity
• Abdominal cavity too warm to produce ______ sperm; man is
sterile
– Inguinal hernia
• Membrane separating abdominal cavity from scrotum gets
ruptured, ___________ can be forced into _________
• Blood flow of testes and small intestine in danger due to pressure
– Ruptured Testicle
• Forceful, direct blow
• _____% from sports related injuries
• If treated within 72 hours, 80% chance of salvaging damaged
testicle
u
y
Testes
• Male gonads
•
• Produce sex cells (sperm) in
coiled seminiferous tubules
Seminiferous Tubules
• Housed in the testes,
which are about 5 cm
long.
• If uncoiled, they would
measure _____m
• Lined with spermproducing cells called
______________
• Site of spermatogenesis,
or the _________ of
sperm cells
Epididymus
• Tightly coiled tube
connecting the
________________
to the
________________
where sperm are
mature and become
motile
Vas Deferens
• Tube that conducts
sperm towards the
_______
• Carries sperm from the
testis to the ejaculatory
duct
Ductus Deferens
• A storage duct that carries sperm and
fluids (semen)from the epididymis to the
ejaculatory duct
Ejaculatory Duct
• A tubule formed where the vas deferens and seminal
vessicle ducts meet, opens into _______
• Stores the sperm from vas deferens until needed
• Propels the movement of semen into the urethra
Urethra
• A duct, shared by the
urinary and
reproductive systems,
that carries fluid
through the penis
• At any time, urethra
conducts either urine
or semen,
Penis
• Used to transfer
sperm from the male
to the female
reproductive tract
• Glans Penis
–
Foreskin
• A flap of skin that
protects the
surrounds and
protects the glans
penis
• The tissue that is
removed during
_____________
Semen
• Secretion consisting of
sperm and fluids
• ~1 tsp produced during
ejaculation which
contains roughly ______ million sperm
• 2-3% sperm, remaining
is seminal fluid
Vasectomy
• Common procedure to
prevent pregnancy
• Vas deferens from
each testicle is
_____________
• Performed at Dr’s
office with a _______
anesthetic
Success Rates of Birth Control
Method
Used By
Type
Dr Rx?
Actual
Failure Rate
Reversible
Abstinence
Both M & F
Natural
No
0.0%
Yes
Condom
Male
Barrier
No
1-33%
Yes
Hormone
Implant
Female
Hormonal
Yes
0.2%
Yes
No method
Both M & F
-
No
>85%
--
Oral
Female
Hormonal
Yes
0.16-3%
Yes
Vasectomy
Male
Surgical
Yes
0.02-0.2%
Possibly
Withdrawal
Male
Natural
No
19%
Yes
Adapted from Adapted from: 1. Trussell J, Hatcher RA, Cates W, Stewart FH, Kost K. A Guide to Interpreting Contraceptive Efficacy Studies. Obstetrics
and Gynecology 1990; 76:558-67. 2. Mishell DR, Jr. Contraception. New England Journal of Medicine 1989; 320: 777-787.
The Glands
•
•
•
•
Seminal vessicle
Prostate gland
Cowper`s gland
Responsible for nourishing and lubricating
sperm
• Part of the endocrine system
Seminal vesicles
• Produces a mucouslike fluid containing
________ (sugar)
which provides
_______ for sperm
Prostate gland
• Produces mucus-like alkaline fluid that neutralizes
the ______ from ______ in the urethra
Cowper’s gland
• Secretes
alkaline mucuslike fluids into
the urethra
Can you...?
• Identify the following structures on the diagram
–
–
–
–
–
–
–
–
–
–
–
–
Cowper`s gland
Prostate gland
Vas deferens
Ejaculatory duct
Urethra
Seminal vessicles
Seminiferous tubule
Epididymus
Testicles
Scrotum
Penis
Glans penis
• Sexual arousal:
• _______________ nerve causes arteries
leading to the penis to _______, increasing
blood flow
• Spongy tissue of the penis swells,
_____________ veins that carry blood away
from the penis
• Penis engorges with blood and becomes erect
Spermatogenesis
1. Spermatogonia (______________________)
divide to form spermacytes
2. Spermacytes differentiate into spermatids
• Spermatids
–
– Contain only __ chromosomes (half as much as
other cells)
– 9-10 weeks to differentiate into sperm cell
Spermatogenesis
3. Sertoli cells found in the seminiferous tubules
________ the developing sperm cells to
maturity
• Sertoli cells
– Provide a _______ between blood and testes
– Barrier controls the entry/exit of hormones,
nutrients; ________ the sperm cells
– If barrier is damaged, body develops antibodies
against its own sperm
Spermatogenesis
4. Sperm mature in the epididymis; defective
sperm are ________ here by the __________
system
Sperm
• Swimming motion begins
after __ days in the
epididymis
• Streamlined design
(reduced cytoplasm) for
motion
• Limited cytoplasm =
_________________
• Mitochondria found
between the nucleus and
the flagellum (propulsion)
• Acrosome-cap on head of
sperm cell, filled with
________ that dissolve the
outer coating of the egg
Seminal Fluid
• Ejaculation is the process where semen leaves
a man body through the penis
• Sperm is forced to the base of the penis by the
___________ of the vas deferens, seminal
vesicles, ejaculatory duct and prostate gland
• Strong muscular contractions force the semen
into the urethra and out the penis
Seminal Fluid
• Seminal vesicles
– Release fluid containing fructose and prostaglandins
• Fructose-energy supply
• Prostaglandins-stimulate rhythmic contractions of smooth muscle
along the female reproductive tract
• Prostate gland
– Secretes an alkaline buffer that protects sperm from acidic
environment of vagina
• Cowpers gland
– Secretes mucus-rich fluid prior to ejaculation
– Protects sperm from acids in the urethra
– May help with sperm motility
Affect of Hormones on Male System
• Primary sexual characteristics
– Physical characteristics of an organism that are
directly involved in reproduction
–
• Secondary sexual characteristics
– ________ features other than reproductive
organs, that indicate gender
Testosterone
• Primary male sex hormone produced in
insterstitial cells of testes
• Triggers ___________ of tests and penis, as
well as spermatogenesis
• Promotes secondary characteristics
–
– Growth of larynx (deepening voice)
– Strengthening of muscles
–
• __________ and _________ control production
of sperm and sex hormones
• Pituitary- produces and stores gonadotropic
hormones (gonadotropins) which regulate the
testes
• 2 gonadotropins
–
• Turns on production of sperm cells in seminiferous tubules
–
• Promotes production of testosterone by interstitial cells
Male Reproductive Hormones
Hormone
Location
Function
Pituitary gland
Triggers production of
sperm cells in seminiferous
tubules
Interstitial cells
Luteinizing hormone
Stimulates secretion of FSH
and LH
• Negative feedback systems ensure that sperm cells and
testosterone are maintained at constant levels
• When testosterone is low:
–
–
–
–
–
–
Hypothalamus secretes _____
GnRH activates pituitary gland to release _____ and L____
FSH acts on sperm-producing cells in seminiferous tubules
LH stimulates __________ production
Testosterone stimulates ____________
Negative feedback regulates LH and testosterone
• High testosterone _________ LH production directly by feedback inhibition of
LH release from the pituitary and indirectly from GnRH release from the
hypothalamus
• When hypothalamus detects _____ testosterone, releases less GnRH, which
leads to less LH
• Decreased GnRH slows down LH, which means lower testosterone