HUMAN REPRODUCTION © PDST Home Economics

THE PURPOSE OF SEXUAL REPRODUCTION IS TO MAKE NEW INDIVIDUALS SO THAT A SPECIES MAY CONTINUE

Female Reproductive System FALLOPIAN TUBE (OVIDUCT) OVARY WOMB (UTERUS) CERVICAL CANAL CERVIX VAGINA

Structure of the Uterus It 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 Uterus It 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 Ovaries They 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 Tubes They 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 Cervix It 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 Vagina It serves as a passageway for the menstrual blood. It forms part of the birthing canal. It is the site of penetration during intercourse.

The vulva is made up of the following: The external organs of female reproductive system are known as the vulva. The vulva is made up of the following: Mons pubis Labia Clitoris

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 CYCLE LINING OF WOMB BEGINS TO BREAK DOWN MENSTRUATION (A PERIOD) OVULATION (EGG RELEASED) LINING OF WOMB BUILDS UP LINING OF WOMB BUILDS UP FERTILE 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

PREGNANCY The 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 WOMB PLACENTA FOETUS UMBILICAL CORD AMNIOTIC FLUID CERVIX VAGINA (BIRTH CANAL)

8 months 4 weeks 5 months

placenta Umbilical cord

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 UMBILICAL CORD

PARTS OF THE MALE REPRODUCTIVE SYSTEM BLADDER SPERM DUCT PROSTATE GLAND URETHRA TESTICLE EPIDIDYMIS SCROTUM PENIS

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 Penis It 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 Scrotum It 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.