The Human
Reproductive
Systems
Functions of the reproductive
systems
– To ensure that the sex cells, sperm and ova,
are produced and are ready to fertilise each
other.
– To prepare the uterus to receive the fertilised
egg and then modify the uterus as required as
the embryo and then the foetus develop.
– To ensure that the uterus goes through the
processes which expel the baby and the
placenta (afterbirth).
Components of these systems
Male:
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Testis (_tes)
Scrotum
Epididymis (_mes)
Vas deferens (vasa
deferentia)
Cowper’s gland
(bulbourethral gland)
Seminal vesicle
Prostate gland
Penis
Sperm
Female
• Ovary (_ies)
• Follicles
(Corpus luteum)
• Fimbriae
• Oviducts (Fallopian
tubes)
• Uterus (and cervix)
• Vagina
• Clitoris
The male system
The male system
Scrotum
• The scrotum is very temperature sensitive
to ensure that the testes are at the
optimum temperature for sperm
production.
• Human body temperature is around 37oC.
• Optimal sperm production is at 35oC.
• The scrotum has many tiny muscles which
adjust the testicular temperature by
moving the testes closer to or further from
the body.
Testes
• The testicle (from
Latin testiculus),
diminutive of testis,
meaning "witness"
[of virility], plural
testes.
• The sperm are
produced in the
seminiferous
tubules.
Epididymis
• The epididymis (_mes) is
a long and convoluted
tube behind the testis.
• About 100 million sperm
are produced each day.
• The sperm enter this tube
in an immature form and
could spend up to three
months maturing.
• The sperm will not have
the capacity to fertilise an
ovum until they have
reached the uterus.
Vas deferens
• The vasa
deferentia carry
the sperm from the
epididymes to the
prostate gland just
prior to ejaculation.
Prostate gland
• There are a number of glands that add “juices”
to the sperm to make the semen.
• These are:
– Cowper’s gland or bulbourethral gland
– Seminal vesicles
– Prostate gland
• These juices provide fluid, fructose and other
components to ensure that the sperm can be
transferred to the female and be able to survive
long enough to fertilise the ovum.
Prostate cancer
• Most prostate cancers are slow growing; however, there
are cases of aggressive prostate cancers. The cancer cells
may metastasize (spread) from the prostate to other parts
of the body, particularly the bones and lymph nodes.
Prostate cancer may cause pain, difficulty in urinating,
problems during sexual intercourse or erectile function.
• the Gleason score is a helpful tool in classifying the stage
and grade of prostate cancer. The Gleason score can
range from 2 through 10.
• Treatment options for prostate cancer with intent to cure
are primarily surgery, radiation therapy (eg brachytherapy)
and proton therapy.
Penis
• Besides urinating, the other
main function of the penis
is to deliver semen
containing sperm to the
female’s cervix.
• The only way that this can
be done effectively
(naturally) is by having an
erection.
• For an erection to happen
the spongy tissue in the
penis must be engorged
with blood producing a high
hydrostatic pressure
Ejaculation
• Ejaculation occurs when the prostate gland
contracts strongly a number of times releasing
semen into the urethra.
• It is at this stage that sperm delivered by the vas
deferens to the urethra is mixed with the semen.
• An ejaculate can vary between 2 mL and 10 mL
with the average being about 5 mL (a teaspoon)
and can contain up to 500 million sperm.
• Sperm are so small that they occupy about 0.1%
of an ejaculate.
The female system
The female system
Ovaries
• The ovaries
– Produce two hormones
(oestrogen and
progesterone) that
prepare the body for
pregnancy,
– Produce a follicle a
month in which the
ovum (egg) develops,
– After ovulation the
follicle becomes the
corpus luteum which
then produces
progesterone.
Polycystic Ovarian Syndrome
• The causes of PCOS are unknown. In some cases, it seems to run
in the family whereas for other women the condition only occurs
when they are overweight.
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Women who have PCOS may have problems such as:
Irregular menstrual cycles – menstruation may be less frequent
due to less frequent ovulation, and may be either heavier or lighter
than average.
Amenorrhoea – some women with PCOS do not menstruate, in
some cases for many years.
Obesity – the cause of this is unclear.
Excessive hair growth – may be due to increased testosterone.
Acne – the cause is unclear.
Infertility – related to less frequent or absent ovulation.
There may also be long-term health risks. Recent research suggests
that PCOS is related to insulin resistance and the development of
diabetes. Some women with PCOS develop diabetes, especially if
they are overweight.
Fimbriae
• An ovary is not directly
connected to its adjacent
oviduct. When ovulation
is about to occur, the sex
hormones activate the
fimbriae, causing them to
swell with blood and hit
the ovary in a gentle,
sweeping motion.
• An oocyte (ovum) is
released from the ovary
into the peritoneal
(abdominal) cavity and
the cilia of the fimbriae
sweep the ovum into the
Fallopian tube (oviduct).
Oviduct
• The oviduct (Fallopian
tube) transports the
oocyte (ovum) from
the fimbriae to the
uterus.
• Fertilisation usually
occurs in the oviduct
about a third of the
way from the ovary.
• The fertilised ovum is
called a zygote.
Uterus
• The uterus consists of a body and
a cervix. The cervix protrudes into
the vagina. The uterus is held in
position within the pelvis by
ligaments.
• The reproductive function of the
uterus is to accept a fertilised
ovum. It implants into the
endometrium, and derives
nourishment from blood vessels
which develop exclusively for this
purpose. The fertilised ovum
becomes an embryo, attaches to
a wall of the uterus, creates a
placenta, and, by 12 weeks,
develops into a foetus (gestates)
until childbirth.
Implantation
• This diagram shows the movement of the ovum,
the zygote (first cell) and the dividing cells
moving through the oviduct, into the uterus.
• It is then implanted into the endometrium at
about day 6.
Endometrium
• The endometrium is the
lining of the uterus
which changes its
thickness according to
the stage of the
reproductive cycle.
• These changes are
controlled by the
changing hormones.
• The thickness ranges
from about 6 mm to
about 14 mm.
Hysterectomy
• Hysterectomy is the surgical removal of the womb (uterus),
with or without the removal of the ovaries.
• The conditions that may be treated by hysterectomy include:
– Fibroids, which are non-malignant growths inside the muscular walls
of the uterus.
– Heavy or irregular menstrual periods.
– Severe period pain, or dysmenorrhoea.
– Cancer of the cervix, uterus or ovaries.
– Endometriosis, a condition characterised by the migration of cells
from the uterine lining to other areas of the body.
– Prolapse, which means the uterus falls into the vagina because of
loose ligaments or damage to the pelvic floor muscles.
– Pelvic inflammatory disease (PID), caused by bacterial infection.
Vagina
• The vagina (from Latin vagĭna, literally
“sheath" or “scabbard") is an elastic
fibromuscular tubular tract leading from
the uterus to the exterior of the body.
• It can expand to be able to allow the birth
of a baby.
Clitoris
• The clitoris is a sexual
organ that is present only
in female mammals. In
humans, the visible
button-like portion is
located near the anterior
junction of the labia
minora, above the
opening of the urethra
and vagina.
• The clitoris is much more
extensive than most
people imagine.
• The penis and clitoris
have the same embryonic
origins.
Conditions of the female
reproductive system
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Endometriosis
Polycystic ovarian syndrome
Ectopic pregnancy
Pelvic Inflammatory Disease
Cervical cancer
Ovarian cancer
Fibroid tumours
Gestation
Gestation
First trimester
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In medicine, pregnancy is often defined
as beginning when the developing embryo
becomes implanted into the endometrial
lining of a woman's uterus.
The first two weeks of the first trimester
are calculated as the first two weeks of
pregnancy even though the pregnancy
does not actually exist.
The 5th week marks the start of the
embryonic period when the baby's brain,
spinal cord, heart and other organs begin
to form.
In the 6th week, the baby will be
developing basic facial features and its
arms and legs start to grow.
In the 8th week, the baby starts moving
and in the next three weeks, the baby's
toes, neck and genitals develop.
By the end of the first trimester, the foetus
will be about 76 mm long and will weigh
approximately 28 g.
Second trimester
• Weeks 13 to 28 of the
pregnancy are called the
second trimester.
• By the 20th week the
uterus can expand up to
20 times its normal size
during pregnancy.
• The placenta fully
functions at this time and
the foetus makes insulin
and urinates.
• The reproductive organs
distinguish the foetus as
male or female.
Third trimester
• The foetus grows most rapidly during this stage, gaining
up to 28 g per day.
• Movement of the foetus becomes stronger and more
frequent and via improved brain, eye, and muscle
function the foetus is prepared for ex utero viability.
• Brain synapses begin forming at 17 weeks, and at about
week 28 begin to multiply at a rapid pace which
continues until 3–4 months after birth.
Embryonic and foetal
development
Embryo at 4
weeks after
fertilisation
Embryo at 8
weeks after
fertilisation
Foetus at 18
weeks after
fertilisation
Foetus at 38
weeks after
fertilisation
Three stages of Birth