Transcript The Male Reproductive System

An Introductory
By: Ashlee Blannett
Olivia Nevolas
Samantha Evarts
Jessica Hollister
The Male Reproductive System
 The purpose of the organs of the male reproductive
system is to perform the following functions:
 To produce, maintain, and transport sperm (the male
reproductive cells) and protective fluid (semen)
 To discharge sperm within the female reproductive
tract
 To produce and secrete male sex hormones responsible
for maintaining the male reproductive system
The External Male Reproductive
System
 Unlike the female reproductive system, most of the
male reproductive system is located outside of the
body.
 These external structures include the penis, scrotum,
and testicles.
Penis
 Penis: This is the male organ used in sexual intercourse.
 It has three parts
 the root, which attaches to the wall of the abdomen;
 the body, or shaft;
 and the glans, which is the cone-shaped part at the end
of the penis.
Penis
 The body of the penis is cylindrical in shape and
consists of three circular shaped chambers.
 These chambers are made up of special, spongelike tissue.
 This tissue contains thousands of large spaces that
fill with blood when the man becomes excited.
 As the penis fills with blood, it becomes rigid and
erect.
 Semen, which contains
sperm (reproductive cells),
is expelled (ejaculated)
through the end of the
penis.
 When the penis is erect, the
flow of urine is blocked
from the urethra, allowing
only semen to be ejaculated
at orgasm.
Semen
 This is the loose pouch-like sac of skin
Scrotum
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that hangs behind and below the penis.
It contains the testicles (also called
testes), as well as many nerves and blood
vessels.
The scrotum acts as a "climate control
system" for the testes.
For normal sperm development, the
testes must be at a temperature slightly
cooler than body temperature.
Special muscles in the wall of the scrotum
allow it to contract and relax, moving the
testicles closer to the body for warmth or
farther away from the body to cool the
temperature.
Testicles (Testes)
 These are oval organs about the size of large olives
that lie in the scrotum, secured at either end by a
structure called the spermatic cord.
 Most men have two testes.
 The testes are responsible for making testosterone,
the primary male sex hormone, and for generating
sperm.
Testicles (Testes)
•Within the testes are coiled masses of tubes
called seminiferous tubules.
•These tubes are responsible for producing
sperm cells.
The Internal Male Reproductive
System
 The internal organs of the male reproductive system,
also called accessory organs, include the following:
Epididymis
 It is a long, coiled tube
that rests on the
backside of each
testicle.
 It transports and stores
sperm cells that are
produced in the testes.
Epididymis
 It also is the job of the epididymis to bring the
sperm to maturity, since the sperm that emerge
from the testes are immature and incapable of
fertilization.
 Contractions force the sperm into the vas deferens.
Vas Deferens
 The vas deferens is a long, muscular tube that travels
from the epididymis into the pelvic cavity, to just
behind the bladder.
 The vas deferens transports mature sperm to the
urethra, the tube that carries urine or sperm to outside
of the body, in preparation for ejaculation.
Ejaculatory Ducts
 These are formed by the fusion of the vas deferens and
the seminal vesicles.
 The ejaculatory ducts empty into the urethra.
Urethra
 The urethra is the tube that
carries urine from the bladder to
outside of the body.
 It has the additional function of
ejaculating semen.
 When the penis is erect, the flow
of urine is blocked from the
urethra, allowing only semen to
be ejaculated.
Internal : Seminal Vesicles
 The seminal vesicles are sac-like pouches that attach to
the vas deferens near the base of the bladder.
 The seminal vesicles produce a sugar-rich fluid
(fructose) that provides sperm with a source of energy
to help them move.
 The fluid of the seminal vesicles makes up most of the
volume of a man's ejaculatory fluid, or ejaculate.
Prostate Glands
 The prostate gland is a walnut-sized
structure that is located below the
urinary bladder in front of the rectum.
 The prostate gland contributes
additional fluid to the ejaculate.
 Prostate fluids also help to nourish the
sperm.
 The urethra, which carries the
ejaculate to be expelled, runs through
the center of the prostate gland.
Bulbourethral Glands
 Also called Cowper's glands,
these are pea-sized structures
located on the sides of the
urethra just below the prostate
gland.
 These glands produce a clear,
slippery fluid that empties
directly into the urethra.
 This fluid serves to lubricate the
urethra and to neutralize any
acidity that may be present due
to residual drops of urine in the
urethra.
How It Works
 The entire male reproductive system is dependent
on hormones, which are chemicals that regulate
the activity of many different types of cells or
organs. The primary hormones involved in the
male reproductive system are follicle-stimulating
hormone, luteinizing hormone, and testosterone.
How It Works
 Follicle-stimulating hormone is necessary for
sperm production (spermatogenesis) and
luteinizing hormone stimulates the production of
testosterone, which is also needed to make sperm.
 Testosterone is responsible for the development of
male characteristics, including muscle mass and
strength, fat distribution, bone mass, facial hair
growth, voice change, and sex drive.
Sperm
 Looking somewhat like a particularly fat-headed
worm or perhaps a one-legged octopus, the human
sperm cell has three main, distinct parts and two
structures that merit special description.
 The main parts are the head, middle and tail, while
the parts deserving more than a cursory look are
the acrosome and the mitochondria.
Sperm Head
 The head of a human sperm cell consists of an
upper half (an acrosome) and a lower half that
combine to cover and protect the nucleus that
contains chromosomes.
 The capsule-shaped head of the sperm cell also
contains like gel-like material known as cytoplasm
that support the nucleus.
Sperm Nucleus/Chromosomes
 The sperm's nucleus contains the 23 male
chromosomes.
 After implantation, the male chromosomes
combine with 23 female chromosomes in the
ovum's nucleus to form a new set of complete
human genetic material.
Sperm Middle/Mitochondria
 The middle part of the sperm consists of
mitochondria.
 Often described as the "power plants" of cells,
mitochondria perform the final stage of converting a
simple sugar into a substance known as adenosine
triphosphate, or ATP, that cells can use as fuel.
 Mitochondria make ATP from a stored chemical called
adenosine diphosphate, and the operations of
mitochondria allow sperm cells to live for two to three
days outside of a man's body.
Sperm Tail
 Also known as a flagellum, the sperm's tail propels the
cell through the penis, vagina and uterus to get the cell
to the ovum.
 The tail's motion is circular, like a boat's propeller.
Sperm cells "compete" for implantation.
 Typically only one, if any, gets through the cell wall of
the ovum.
 A long tail benefits a sperm cell by allowing it move
faster and exert more force when its cell encounters
the ovum.
Development of Sperm
 Males do not begin to produce sperm until puberty,
when testosterone begins to exert its influence on
overall male development and growth.
 Spermatogenesis is driven by testosterone production
in the Leydig cells of the testes.
 Under the influence of luteinizing hormone (LH) and
follicle-stimulating hormone (FSH), which are
released from the anterior pituitary, the testes begin to
produce sperm in a four-step process of development:
spermatogonia, spermatocyte, spermatid,
spermatozoon.
Development of Sperm
 This process is governed by a negative feedback loop,
with testosterone acting as the primary negative
feedback component that slows LH and FSH secretion.
 Inhibin, released during spermatogenesis, also
specifically inhibits activity or down-regulates FSH.
 This feedback system can be overridden by the
administration of exogenous testosterone, or
medications such as luteinizing hormone-releasing
hormone antagonists, both of which stop the body's
own production of testosterone (and halt
spermatogenesis as well).
Effects of Alcohol on System
 Alcohol causes loss of libido, impotence, and sterility
in males.
 Direct damage to testicular cells and impairment of
control centers in the brain may help explain the
sexual dysfunction.
 Hypogonadism may be caused by direct effects of
alcohol on the testis; it can also be caused by effects of
alcohol on parts of the brain that regulate gonadal
function.
 These parts of the brain include the hypothalamus,
located approximately in the center of the brain, and
the pituitary gland, located at the base of the brain just
below the hypothalamus.