Transcript Document
The Male Reproductive System
This consists of:
A pair of testes situated in a scrotum
The epididymis, vas deferens,
ejaculatory duct and urethra
The accessory glands: seminal
vesicles, prostate glands and Cowper’s
glands
Penis
The Male Reproductive System
The Testis
Testis are the male sex organs,
They occur in a bag like scrotum which
lies outside the abdominal cavity
The testes produce sperm, which
cannot survive long at body
temperature. Sperm leave the body
in semen, a fluid produced by the
seminal vesicles.
Within each testis are found seminiferous
tubules
The Testis
These are lined by germinal epithelium
cells
These cells produce the spermatozoa
by spermatogenesis
Inside the seminiferous tubules, there
are specialised cells called sertoli cells
In males, the sex cells are called sperm.
Sex cells – sperm
tail
middle piece
cell membrane
head
nucleus containing DNA
Sperm are produced in sex organs called testes.
The Testis
These cells secrete the male sex hormone
called testosterone
When sexual maturity (puberty) occurs,
testosterone is responsible for the
development of male characteristics
Such as
The growth of hair on the face, armpits and
pubic areas
Lowering of voice
Development of muscles which give males
their shape such as broad shoulders
What happens during puberty?
Humans are born with a complete set of sex
organs. However, they do not usually become
active until between the ages of 10 and 18.
In males, the testes start to make sperm, and
in females, the ovaries start to release eggs.
This stage of development is called
puberty.
During this important time, many changes
take place in the bodies of young men and
women.
Ducts responsible for carrying the
spermatozoa from the testis to the peni
The tubes responsible for carrying
the spermatozoa include:
Epididymis
Vas deferens
ejaculatory ducts
urethra
The Testis
These cells are rich in glycogen
This glycogen serves as nutrients for
the spermatids as they develop into
sperm cells
Between the seminiferous tubules are
intestitial cells called cells of Leydig
Tubes Responsible for carrying
the spermatozoa
The epididymis is a coiled tube lying
outside the testis but within the
scrotum
It leads from seminiferous tubules,
stores sperm temporarily
Later passes the sperm into vas
deferens
Tubes Responsible for carrying
the spermatozoa- vas deferens
The vas deferens (sperm duct)
carries the spermatozoa from the
epididymis
through the abdomen into the
ejaculatory duct
Tubes Responsible for carrying the
spermatozoa- ejaculatory ducts
The two ejaculatory ducts join the
urethra just after it leaves the bladder
Contraction of the muscular wall of the
ducts forces its content (semen)
through the urethra
Tubes Responsible for carrying
the spermatozoa - urethra
The urethra is a tube which runs
through the penis and opens at the tip
It is a common tube for the passage of
urine or semen
Accessory Glands
The tubes transporting the
spermatozoa are joined by seminal
vesicles:
prostate glands
and Cowper’s gland
Accessory Glands
These glands:
Secrete a fluid which promotes
movement of the spermatozoa
Secretes a fluid which provides
nutrition to the spermatozoa
Functions of the
accessory glands
Seminal Vesicles
Prostate gland
Secretes a fluid
that nourishes
and enables
sperm to move.
Secretes an
alkaline fluid that
neutralizes the
acidity.
Cowper’s glands
Two glands by
prostate that
secrete a fluid
that neutralizes
acidity.
The Penis
The penis is the external reproductive
organ of the male
Made up of spongy tissue
Becomes filled with blood causing the
penis to become erect
Then inserted into the female organ
The male reproductive system
The female reproductive
system
An overview
This system consists of:
A pair of ovaries
A fallopian tube or oviduct
The uterus or womb
The vagina or birth canal
The vulva or external opening
The Ovaries
The ovaries are the female sex organs
Occur un the lower part of the abdominal cavity
and are held in place by ligaments
Each ovary is made up of a covering of germinal
epithelium with a large number of follicles within
it
The Ovaries
The germinal epithelium produces the follicles
Oogenesis takes place within the follicles to
produce the ova
Follicles secrete the female hormones oestrogen
and progesterone
The Ovaries
When puberty occurs, the female sex hormones
are responsible for the development of female
characteristics
Such as:
Increase in size of breasts
Development of pubic and armpit hair
And menstruation
The fallopian tubes (oviducts)
The fallopian tubes convey ova from
the ovaries to the uterus
Upper part is expanded into ciliated
funnels
Partially enclosed ovaries
The Uterus
Two fallopian tubes open into the uterus which is
pear shaped, hollow organ with muscular walls
The ling of the uterus is called endometrium, is
richly supplied with blood vessels
The Uterus
The neck of the uterus, called the cervix, extends
into the vagina
The uterus serves for the attachment of the
embryo
Fertilisation takes place
Gametogenesis
Gametogenesis
Spermatogenesis refers to the process by which
spermatozoa are produced from the germinal
epithelium of the testis
Oogenesis is the process where ova is produced
from germinal epithelium of the ovaries
Spermatogenesis
At puberty, the germinal epithelial cells
lining the seminiferous tubules start to
produce spermatozoa by meiosis
Each germinal epithelium is diploid and
in humans the diploid number is 46
Since the sperm is produced by meiosis,
each one will be haploid with 22 single
chromosome and X or Y chromosome
Spermatogenesis
The process is as follows:
Cells of germinal epithelium become
actively dividing cells called
spermatogonia
Each spermatogonium, which is diploid
(2n), enlarges to become a primary
spermatocyte (also 2n)
Spermatogenesis
Primary spermatocyte undergoes the
first meiotic division forming 2 haploid
secondary spermatocytes
Each secondary spermatocyte
undergoes the second meiotic division to
produce 2 spermatids
Each spermatid matures to form a
spermatozoan
Each spermatozoan is made up of a
head, a middle-piece and a tail
Hormonal Control of the
Menstrual Cycle
Inside the ovary of females there are large sac
like structures called Graafian follicles
Each follicle contains a maturing ovum
The growth of he ovum inside the Graafian
follicle is controlled by follicle stimulating
hormone (FSH)
Secreted by anterior lobe of the hypophysis or
pituitary gland
These are produced by the germinal epithelium
Hormonal Control of the
Menstrual Cycle
Between day 11 and 16, ovulation takes place
During ovulation, a single graaffian follicle ruptures
and sets free an ovum
The ovum is collected by the funnel of the fallopian
tube and passes down toward the uterus
Hormonal Control of the Menstrual
Cycle
Luteinising hormone (LH),
also produced by the anterior lobe,
helps convert ruptured follicle into a
structure called corpus luteum
Hormonal Control of the Menstrual
Cycle
If the ovum is fertilized by a sperm cell
Corpus luteum secretes hormone progesterone
Makes certain that the embryo remains attached to
the uterus wall
Ensures pregnancy remains
Hormonal Control of the Menstrual
Cycle
If the ovum is not fertilized, the corpus luteum is
destroyed
Little progesterone is secreted and menstruation occurs
During menstruation, the endometrium lining of the
uterus comes off as the menstrual period
Hormonal Control of the Menstrual
Cycle
This is accompanied by bleeding
Menstruation takes place about 14 days after ovulation
The next egg is then released about 14 days after
menstruation
Hormonal Control of the Menstrual
Cycle
There are 2 separate sub-cycles during the
menstrual cycle
The ovarian cycle
The uterine cycle
Hormonal Control of the Menstrual
Cycle
The ovarian cycle describes what happens in the ovary
The uterine cycle describes the changes that are made
in the uterus lining
A graafian follicle, at different stages, produces
oestregen and progesterone
Hormonal Control of the Menstrual
Cycle
These hormones control what happens ti the uterine
wall
The cycles are closely related
The entire menstrual cycle is controlled by hormones
produced by anterior lobe of hypophysis
Fertilisation and implantation
During sexual intercourse/ copulation. Penis is placed
into vagina and spermatozoan is released
It swims up to uterus and into fallopian tube
Fertilisation and implantation
If an ovum is present in this time, the sperm will fertilise it
Resulting in a diploid zygote
The moment of fertilisation is called conception
Spermatozoan has 22 single autosomes and X or Y
chromosome
Ovum has 22 single autosomes and an X chromosome
Fertilisation and implantation
Fertilisation usually takes place in the upper part of
the fallopian tube
There is not enough space here for a baby to grow
It has to move down to the uterus for more
Fig. 29.19
Fertilisation and implantation
It is moved down the fallopian tube by beating oh fine
hair-like structures on the walls
As it passes down into the uterus, it divides by mitosis
This happens many times
Fertilisation and implantation
All cells are identical
By the time it reaches the uterus it is a hollow ball of
cells called blastocyst
By the ninth day, th blastocyct is now called and
embryo
Fertilisation and implantation
The process of developing the embryo and becoming
attached to the uterine wall is called implantation
In the meantime, the corpus luteum has secreted
progesterone
Fertilisation and implantation
The endometrium lining of the uterus has become
thicker and
supplied with blood vessels
Embryonic development and
Pregnancy
Another term for pregnancy is the gestation period
It lasts for about 280 days which is slightly more than 9
months
Embryonic development and
Pregnancy
Embryo increases in shape and size as it grows
By 12 weeks the embryo has grown quite a lot, and will
look clearly like a human baby
It is now called the foetus
Development of the extra-embryonic
membranes
Soon after the blastocyst itself to the uterus wall, 2
membranes develop around it
Extra-embryonic membranes
Development of the extra-embryonic
membranes
These membranes are:
The chronian on the outside, forms chronic
villi
An amnion, on the inside, with amniotic
cavity filled with amniotic fluid
Development of the extraembryonic membranes
Chronic villi with uterine tissue make up the placenta
A hollow rope-like tube called umbilical cord,
attaches the embryo to the placenta
Development of the extraembryonic membranes
The placenta has the following functions:
Attachment of embryo to mother
Diffusion of desolved food from mother to
foetus
Development of the extraembryonic membranes
Diffusion of oxygen from mother to foetus
and carbon dioxide from foetus to mother
Development of the extraembryonic membranes
After 12 weeks of pregnancy it secretes its own
progesterone which maintains pregnany
Development of the extraembryonic membranes
The amniotic fluid has the following functions:
Shock absorber
Prevents dehydration
Development of the extraembryonic membranes
Keeps foetus within a small temperature range
Allows free foetal movement for growth and
development
Development of the extraembryonic membranes
The umbilical cord contains the umbilical
artery and vein
The artery carries deoxygenated blood
with nitrogenous wastes from the embryo
to the placenta
The vein carries oxygenated blood and
food
Birth
Occurs about 280 days after fertilisation, this happens
in 3 stages
Stage 1:
Uterus contracts
Head pushed against cervix
Membranes break
Cervix dilates
Birth
Stage 2:
Baby forced out through birth canal
Umbilical cord cut
Baby handed to mother
Stage3:
Placenta becomes loose
Placenta pushed out as the ”after-birth
Contraception
Method
Natural
Methods
Description
Withdrawal
The penis is removed out of
the vagina before ejaculation
but it is not safe method
because many sperms are
released during sexual
intercourse
Rhythm
method
Sexual intercourse is avoided
during ovulation. This is not a
safe method of contraception
because it is impossible to be
100 % sure when ovulation will
occur
Contraception
Method
Barrier
methods
Description
Condom
Femidom
IUD/loop
Diaphragm
Act as a barrier to stop sperms
from entering the vagina
Act as a barrier to stop sperms
from getting into the
uterus/Fallopian tubes
It prevents fertilised
eggs/embryos from becoming
attached to the uterine wall and
is highly effective
It covers the cervical opening
and prevents sperm from
entering the uterus and is fairly
effective
Contraception
Method
Description
Chemical Spermicides
/drug
treatment
It contains a chemical substance that kills
sperm and acts as a barrier/prevents
sperm from entering the Fallopian tubes.
They are not very reliable on their own.
Contraceptive Contains artificially produced hormones
pills
which prevents the production of
eggs/ovulation. Signalling the body that it
is already pregnant. It changes the lining of
the cervix/womb. It is a very reliable
method.
Contraceptive It contains progesterone/combination of
injections
oestrogen and progesterone which stops
ovulation/changes the lining of the womv
and the cervix. It works for 2 to 3 months
and are very effective.
Contraception
Method
Surgical
methods
Description
Male
Sterilisation
Female
Sterilisation
The sperm ducts are cut and
tied. Semen without sperm is
produced and is a very
effective method of
contraception.
The Fallopian tubes are cut
and tied during a small surgical
operation preventing the fusion
of sperm and egg
syphilis
Caused by spiral bacterium, treponema
pallidum
Transmission:
Sex with infected partner, mother to child
Symptoms:
Nodules on sex organs
Rash over the body
Sore throat and aching muscles
syphilis
Can attack tissue or organ including skin
Lead to blindness and death
Treatment:
Antibiotics in early stages
gonorrhoea
Causes:
Coccus bacterium, gonococus
Transmission:
Sex with infected person
Symptoms:
Frequent and painful urination, discharge
Sterility in men and woman
gonorrhoea
Treatment:
Antibiotics, penicillin
More difficult to cure in late stages
Prevention of stds
Most stds are life-threatening
For many of them, there is no cure
Medication, nutritious diet and healthy lifestyle
can slow down progress of the disease
Use A B C method
Abstain from sexual activites
Be faithful to your partner
Condomise