Reproductive System
ACCESS H.E.
Human Biology.
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Introduction
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Male and female reproductive systems are different in
shape and structure, but both are specifically designed to
produce, nourish, and transport either the ova or sperm.
Male reproductive system is located both inside and outside
the pelvis.
Male reproductive system consists of: testes, duct system,
accessory glands such as seminal vesicles and prostate, and
the penis.
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Testes
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Description
Function
• The two testes are ovalshaped and grow to about 5
centimeters in length and 3
centimeters in diameter.
• They are suspended in the
scrotum, outside the body.
• Each testicle contain
approximately 200-300
lobules.
• Testes produce and store
millions of sperm cells.
• Testes are also part of the
endocrine system, producing
hormone testosterone.
• Stimulates sperm
production.
• Testosterone is responsible
for the development of the
secondary sexual
characteristics in boys
(deeper voices, bigger
muscles, body/facial hair).
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Duct system
Description
Function
• The duct system consists • Spermatozoa (sperm) is
of :
synthesised in the
• Seminiferous tubule.
seminiferous tubule.
• Epididymis.
• Immature sperm develops in
• Vas deferens.
the epididymis, which is
connected to the vas
deferens.
• The vas deferens provides a
passageway that transports
the semen from the testes.
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Scrotum
Description
Function
• The scrotum is a pouch-like • The scrotum helps to
structure that hangs outside
regulate the temperature of
the pelvis.
the testes.
• It houses the
• The temperature needs to
be kept cooler than body
epididymis and the testes.
temperature to produce sperm.
• The scrotum changes size
and position to maintain the
correct temperature.
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Prostate gland
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Description
Function
• Surrounds the ejaculatory
ducts at the base of the
urethra, just below the
bladder.
• Produces two secretions
that are part of the seminal
fluid.
• One keeps lining of urethra
moist.
• One helps semen to travel
along the urethra and into
the female.
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Seminal vesicle
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Description
Function
• Sac like glands that are
found at the base of the
bladder and are connected
to the prostrate gland.
• Also secretes seminal fluids
that lubricate the duct
system and nourish the
sperm.
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Penis
Description
Function
•
• The penis, which usually hangs limp,
becomes hard when a male is sexually
excited.
• Tissues in the penis fill with blood and it
becomes stiff and erect.
• The rigidity of the erect penis makes it
easier to insert into the female's vagina
during sexual intercourse.
• When the erect penis is stimulated,
muscles around the reproductive organs
contract and force the semen through
the duct system and urethra.
• This process is called ejaculation.
• Each ejaculation can contain up to 500
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million sperm.
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•
•
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The penis is actually made up
of two parts: the shaft and the
glans.
The shaft is the main part of
the penis and the glans is the
tip.
Inside the penis is the urethra,
the channel that carries the
semen to the outside of the
body.
At the end of the glans is a
small slit or opening, which is
where semen and urine exit the
body through the urethra.
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Sperm, male gamete
(reproduction cell)
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Male Reproductive.wmv
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References.
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Male Reproductive.wmv
Baggaley, A. (2001) Human Body. London:
Dorling Kindersley.
Seely, R. et al. (1989) Anatomy and
Physiology. USA:
TimesMirror/MosbyCollege.
Tortora, G. and Grabolski, S. (1993)
Principles of Anatomy and Physiology. USA:
HarperCollins.
Tucker, L. (2002) Anatomy and Physiology.
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Cambridge: Holistic
Therapy.
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Ovaries
Description
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Function
• The ovaries are 2 oval• The ovaries produce, store,
shaped organs that lie to
and release ova into the
the upper right and left of
fallopian tubes in the
the uterus.
process called ovulation.
• Each ovary measures about • The ovaries are also part of
4 to 5 centimeters in a
the endocrine system
grown woman.
because they produce the
• After puberty one ovum is
female sex hormones
released each month.
estrogen and progesterone.
• This process is called
• These hormones are
responsible for female
ovulation.
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secondary
sexual
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characteristics.
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Follicle.
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Small structures on the surface of the
ovaries.
The follicles contain fluid and an ovum.
When an ovum is mature for fertilisation
the follicle splits to release the ovum.
The mature ovum then travels along the
Fallopian tube to the uterus.
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Fallopian tubes
Description
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Function
• There are 2 Fallopian • When an ovum exits an ovary,
tubes, each attached to a
it enters the Fallopian tube.
side of the uterus.
• Once inside the Fallopian
• The Fallopian tubes are
tube the ovum is transported
about 10centimeters long
towards the uterus by
and about as wide as a
peristalsis and tiny hairs
piece of spaghetti.
(cilia) in the tube's lining help
• At the other end of each
push the ovum down the
Fallopian tube is a fringed
narrow passageway toward
area, (fimbriae ends), that
the uterus.
wrap around near the
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ovary.
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Uterus
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Description
Function
• The uterus is shaped like
an upside-down pear.
• It has three layers:
• Endometrium (mucus
membrane
–
columna
epithelial lining).
• Myometrium
(thick
smooth muscle – thickest
in the body).
• Perimetrium (serous
membrane).
• Receives the fertilised ovum
which develops in the
uterus.
• The uterus grows with the
foetus until birth.
• The muscle expands and
contract to accommodate a
growing foetus.
• The muscle helps to push
the baby out during labour.
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Vagina
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Description
Function
• The vagina is a muscular,
hollow tube that extends
from the labia to the
uterus.
• Muscular walls enable it to
expand and contract.
• This allows the vagina to
accommodate something as
wide as a baby.
• The vagina's muscular walls
are lined with mucous
membranes.
• Lubricating fluids keep the
vagina protected, moist and
assist with penetration.
• The vagina serves 2
purposes:
• It is where the penis is
inserted during sexual
intercourse.
• It is the pathway that a
baby takes out of a woman's
body during childbirth.
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External genitalia
Description
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Function
• Mons pubis:
The fleshy • Mons pubis and labia protect
area located above the top
the internal structures such
of the vaginal opening.
as the clitoris.
• Labia (Major and Minor):
Two pairs of skin flaps that
protect
the
external
genitalia
and
urethral
orifice.
• Clitoris:
Small sensory
organ located toward the
front of the vulva where
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the folds of the labia
join.
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Mammary glands
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Description
Function
• The mammary glands are
located in the breasts.
• They consist of 15-20
glandular lobes.
• Inside each lobe are
several smaller lobules.
• The mammary glands act as
reservoirs for the milk.
• They secrete the milk when
stimulated during lactation.
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Menstruation
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When a baby girl is born, her ovaries contain
hundreds of thousands of ova.
The ova remain inactive until puberty begins.
At puberty the pituitary gland starts making
hormones.
The hormones stimulate the ovaries to produce
female sex hormones, including oestrogen.
The secretion of these hormones causes a girl to
develop into a sexually mature woman.
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Mensturation flows.
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Towards the end of puberty, girls begin to release ova as
part of the menstrual cycle.
Approximately once a month, during ovulation, an ovary sends a
tiny ovum into one of the fallopian tubes.
Unless the egg is fertilised by a sperm while in the fallopian
tube, the progesterone levels drop causing the egg to dry up.
The dried up ovum leaves the body about 2 weeks later through
the uterus.
This process is called menstruation.
Blood and tissues from the endometrium of the uterus combine
to form the menstrual flow.
This which usually lasts from 3 to 5 days.
On average, the monthly cycle for an adult woman is 28 days,
but this may range from 23 to 35 days.
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Dysmenorrhoea.
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Painful periods.
Many women also experience abdominal cramps
during the first few days of their period.
These are caused by prostaglandin, a chemical in
the body that makes the smooth muscle in the
uterus contract.
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Fertilisation
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Sexual organs of both sexes are required for reproduction.
The female ovaries produce female gametes (ova).
The male testes produce male gametes (sperm).
Natural fertilisation occurs after sexual intercourse when the penis
deposits seminal fluid into the vagina.
The sperm have a tendency to swim towards the fallopian tube
containing the ovulated ovum due to chemical signals that the sperm
respond to.
They are also assisted in their journey by the cilia that are located in
the cervix, wafting them along.
Once the sperm fuses with the ovum, the ovum membrane adjusts to
prevent any other sperm from entering.
Zygote is the name given to a fertilised ovum.
The zygote develops into a foetus.
Pregnancy will develop over a 40 week period.
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