human reproduction
TRANSCRIPT
© PDST Home Economics
THE PURPOSE OF SEXUAL REPRODUCTION IS TO MAKE NEW INDIVIDUALS SO THAT A
SPECIES MAY CONTINUE
Female Reproductive System
FALLOPIAN FALLOPIAN TUBE TUBE
(OVIDUCT)(OVIDUCT)
OVARYOVARY WOMB WOMB (UTERUS)(UTERUS)
CERVIXCERVIX
VAGINAVAGINA
CERVICALCERVICAL
CANALCANAL
Structure of the UterusIt is also known as the womb.It is a muscular hollow organ.It is the size and shape of an upside down
pear.It is 7.5cm.long and 5cm.wide.It expands during pregnancy to accommodate
the foetus.The lining consists of layers of tissues.The tissues respond to hormonal secretions.These layers thicken every month.This thickened layer acts as a nourishing bed
for the fertilised ovum.
Function of the UterusIt is where the foetus grows and develops.Every month it prepares itself for a possible
pregnancy, if there is a fertilised ovum.If there is no fertilised menstruation occurs.
Structure of the Ovaries They are glands. They are about the size and shape of an
almond. One on either side of the uterus. They are just below the fallopian tubes.
Functions of the OvariesThey secrete the hormones progesterone and
oestrogen. It stores the female sex cells called ova. Ova exist in the body at birth. (not mature as
follicles) After puberty one follicle develops releasing
an ovum every month. This is known as ovulation.
Structure of the Fallopian TubesThey are funnel shaped tubes.They start at the top of the uterus and continue
to the ovaries.
Functions of the Fallopian Tubes
They are a passage way from the ovaries to the uterus.
The ovum travels down these tubes to the uterus.
Fertilisation takes place here.
Sperm swims up these tubes to reach the ovum.
Structure of the Cervix It is the narrow neck of the uterus. It opens into the vagina. It is usually the width of a pencil lead. During childbirth it dilates to allow the passage of
the baby.
Function of the CervixIt forms the first part of the birth canal.
The dilation of the cervix is a measurement used to determine how soon childbirth will begin.
Structure of the Vagina It is a muscular passage. It leads from the cervix to the vulva. During sexual activity the walls fill with blood
causing them to swell.
Functions of the VaginaIt serves as a passageway for the menstrual blood.
It forms part of the birthing canal.
It is the site of penetration during intercourse.
The external organs of female reproductive system are known as the vulva.
The vulva is made up of the following: Mons pubisLabiaClitoris
THE MENSTRUAL CYCLE A girl’s menstrual cycle begins after puberty
and continues until the menopause
On average, it is a 28 day cycle
The cycle is controlled by hormones
The cycle does not take place during pregnancy
THE MENSTRUAL CYCLEMENSTRUATION MENSTRUATION
(A PERIOD)(A PERIOD)
LINING OF LINING OF WOMB WOMB
BUILDS UPBUILDS UP
OVULATION OVULATION (EGG (EGG
RELEASED)RELEASED)
LINING OF LINING OF WOMB WOMB
BUILDS UPBUILDS UP
LINING OF LINING OF WOMB BEGINS WOMB BEGINS
TO BREAK TO BREAK DOWNDOWN
FERTILE PERIODFERTILE PERIOD
The Menstrual Cycle It occurs every 28 days from puberty to
menopause. It occurs only if fertilisation has not taken place.Day 1-5 The endometrium (thick lining of the uterus)
breaks down. This is called menstruation. Meiosis (cell reproduction) occurs in the ovary to
produce a new egg surrounded by the Graafian Follicle.
Day 6-13
Oestrogen is produced by the Graafian Follicle.
Oestrogen also stimulates the endometrium to
thicken again.
One Graafian follicle with one egg develops.
Oestrogen stimulated the production of LH
(leuteinising hormone).
Day 14
The surge of LH stimulates ovulation.
The egg is released from the Graafian Follicle.
The egg enters the fallopian tube.
It can be fertilised for the next 48 hours.
Day 15-26 The corpus luteum (yellow body) develops from the
remains of the Graafian Follicle. This produces progesterone and some oestrogen. The progesterone causes the endometrium to
continue to thicken. It also prevents new eggs from forming. The egg that was released at day 14 will die if it is not
fertilised. If fertilisation did not take place the corpus luteum
begins to break up.
Day 26-28 Oestrogen and progesterone levels decline. The endometrium begins to break down. Day one of the cycle begins.
SEXUAL INTERCOURSE During intercourse, the man places his penis
inside the woman’s vagina
Semen is released (ejaculation), containing hundreds of millions of sperm cells
The sperm enter the womb and swim towards the fallopian tubes
SEXUAL INTERCOURSE Only one sperm can fertilise an egg
This can take place successfully only in the fallopian tube
Fertilisation is also known as conception
PREGNANCY The fertilised egg travels down the fallopian tube,
growing as it does so into a ball of cells
Before a woman can be pregnant, this ball of cells must attach itself to the inside wall of the womb
This step is called implantation
PREGNANCYThe ball of cells grows and becomes an
embryo (up to eight weeks)
Once the embryo is recognisably human, it is called a foetus
It takes 40 weeks (9 months) for the foetus to fully develop inside the womb
PREGNANCY Inside the womb, the foetus is attached
to the placenta by the umbilical cord (which joins to the baby’s navel)
The placenta is attached to the inside wall of the womb
The foetus is surrounded by amniotic fluid, which acts as a shock-absorber and to keep the baby warm
THE FOETUS IN THE WOMB
WOMBWOMB
FOETUSFOETUS
VAGINA (BIRTH CANAL)VAGINA (BIRTH CANAL)
PLACENTAPLACENTA
UMBILICAL UMBILICAL CORDCORDAMNIOTIC FLUIDAMNIOTIC FLUID
CERVIXCERVIX
4 weeks4 weeks5 months5 months
8 months8 months
placenta
UmbilicalUmbilical cordcord
Functions of the Parts: The placenta is the baby’s “life-support”
inside the womb
It filters food and oxygen from the mother’s blood and passes it to the baby
It removes waste such as CO2 from the baby’s blood and passes it to the mother’s blood so that she can excrete it
It also keeps the mother’s and baby’s blood separate, so that the mother’s immune system doesn’t reject the baby
BIRTH During birth, the baby passes down the vagina
and out of the mother’s body
This stage is known as labour
After birth, the umbilical cord must be cut
The baby must now breathe on its own for the first time
CUTTING THE CUTTING THE UMBILICAL CORDUMBILICAL CORD
PARTS OF THE MALE REPRODUCTIVE SYSTEM
PENISPENIS
TESTICLETESTICLE
SPERM SPERM DUCTDUCT PROSTATE PROSTATE
GLANDGLAND
BLADDERBLADDER
URETHRAURETHRA
SCROTUMSCROTUM
EPIDIDYMISEPIDIDYMIS
Structure of the Penis The main external sexual organ of the male. It consists of erectile tissue, foreskin and
urethra. The urethra, a tube runs through the centre
and acts as a duct for urine and semen. The tip of the penis is known as the “glans” This tissue is full of blood vessels. Surrounding the glans is the foreskin which
protects the glans.
Function of the PenisIt is an organ of excretion. (urine)It is an organ of reproduction.
It becomes erect during intercourse.This increases the amount of blood circulating
in the penis. It will become rigid which allows for penetration
into the vagina. It delivers semen.
Structure of the Testes The testes are two glands.
They are within a sac of skin called the
scrotum.
They develop in the abdomen and descend
into the scrotum before birth.
Functions of the Testes They produce sperm. Testosterone (hormone) is responsible for
male sexual characteristics. Sperm is also stores in the testes, because
they must be kept at a slightly lower temperature than average body temperature.
Structure of the Epididymis It is a tightly coiled tube. It straightens out into the sperm duct.
Function of the Epididymis
It stores semen.
It transports semen.
Its where immature sperm develop.
Structure of the Scrotum It is a sac containing the testes, epididymis. It has an outer layer of skin. An inner layer of muscle.
Functions of the ScrotumIt protects the testes keeping them at the right temperature.
The testes are outside the body to keep them cooler.
Structure of Sperm Sperm look like tadpoles. They have a head, middle section and a tail. The tail helps to propel the sperm along the
vagina. The head is the nucleus and has 23
chromosomes.
Function of Sperm It fertilises the ova. The head inserts itself into the ovum and
the tail breaks away. Only one sperm is needed to fertilise an
ovum. The semen is a fluid which contains sperm. Semen is excreted from the prostate gland
and seminal vesicle.
Structure of the Prostrate Gland
It’s a small gland. It lies between the bladder and rectum.
Functions of the Prostrate Gland
It produces two secretions.
One moistens the urethra.
The other is part of the seminal fluid, which helps the semen to travel along the urethra.