It is one of the most important characteristics of life.

REPRODUCTION IN HUMANS

WHAT IS REPRODUCTION?•Reproduction is the life process in which living things give rise to individuals of their own kind. •It ensures perpetuation of their own species. •It brings about variation in the individual to adapt in the given surroundings. •Thus, the individual die but the species is not extinct.

TYPES OF REPRODUCTION Asexual reproduction Sexual reproduction Only one parent is

involved in this type of reproduction.

New individuals are identical to their parent.

Large numbers of new individuals are produced to ensure perpetuation.

Two parents are involved in this type of reproduction.

New individuals are not identical to their parents.

Few numbers of new individuals are produced with varition.

WHAT IS PUBERTY ?Puberty is the period in children's lives

when they experience physical changes by which their bodies eventually become adult bodies that are capable of reproducing.

SECONDARY SEXUAL CHARACTERISTICS :Males Females

Growth of hair on the face, armpits and pubic region

Growth of hair on armpits and pubic region

Voice becomes deeper Breasts develop

Growth of penis and testicles Growth of vagina and uterus

Shoulders grow wider and hevier Pelvis widens

SEXUAL REPRODUCTIONTwo parents are involved.Offspring gets genetic characteristics from both the

parents.Reproduction can be internal or external.External reproduction takes place in fish, frog.Internal reproduction takes place in humans, tortoise,

crocodile.The union of male and female gamete is called

fertilization.This results in formation of zygote which is unicellular.Repetitive cell division of zygote results in formation of

embryo.Embryo divides further to form different kinds of cells and

tissues.

REPRODUCTION IN HUMANSReproduction in humans is sexual reproduction.Fertilization takes places inside mother`s body.The male gamete is called SPERM while female

gamete is called OVUM or EGG.The union of sperm and ovum results in formation of

embryo which develops in mother`s womb.After nine months, mother gives a birth to baby.After the birth, the baby feeds on mother`s milk

secreted by her mammary gland for certain time.As human baby takes birth from mother`s womb,

humans are viviparous animals.(Viviparous animals are animals that give live birth and then provide nutrition for the offspring. )

MALE REPRODUCTIVE SYTEM

MALE REPRODUCTIVE SYTEMThe main organs of male reproductive system are:---testicles or testes---epididymis---vas deferens---prostrate gland and seminal vesicles ---urethra---penisTESTICLES or TESTES :There is one pair of testicles.They are developed inside the body of unborn

male child.

MALE REPRODUCTIVE SYSTEMThey move down to the outside of the body before

the baby is born.They are held in a bag of muscles in scrotum region.They produce male gametes i.e. sperm cells.Production of sperms requires lower temperature

than body temperature.Hence, testicles are situated outside the body in

scrotum region. The sperms are produced inside the testes in long

microscopic tubules called SEMINIFEROUS TUBULES.The sex hormone TESTOSTERONE is also produced

in testes.

MALE REPRODUCTIVE SYSTEMEPIDIDYMIS :They are situated on top and side of every testicles. This is a coiled tube in which sperm cells are collected and matured.VAS DEFERENS :The passage through which sperms travel towards the urethra.PROSTRATE GLAND AND SEMINAL VESICLE :They are separate glandular structures together their secretion is know as semen or ejaculatory fluid.

MALE REPRODUCTIE SYSTEMURETHRA : It runs through the middle of the penis. It is also connected to the urinary bladder. It is the tube through which urine flows. Semen and urine do not flow down the urethra at the same time. Penis : It is cylindrical that delivers the sperms for fertilization. It contains spongy tissue along its length that can fill with blood to make it hard, stiff and erect. The tip of the penis is called GLANS PENIS. Glans penis has large number of receptors and is very sensitive.

MALE REPRODUCTIE SYSTEMGlans penis is covered with a fold of skin called foreskin. Fore skin is removed in CIRCUMCISION.

FEMALE REPRODUCTIVE SYSTEM

FEMALE REPRODUCTIVE SYSTEM

The main organs of female reproductive system are:---ovaries ---uterus---fallopian tubes / oviduct ---vagina OVARIES :Pair of oval shaped organs developed inside the female body. They is present in the lower abdomen and situated on the upper part of the uterus. They produce EGG OR OVUM. They also secrete female hormone, ESTROGEN. At the birth, the ovary contains about 2-4 millions of unmatured eggs.

FEMALE REPRODUCTIVE SYSTEM On puberty some of the eggs become matured. A matured women releases one ovum every month as a part of MENSTRUAL CYCLE. UTERUS :It is the muscular organ present in the lower

abdomen. Muscles of uterus have the ability to contract and expand. Growing foetus is accommodated in uterus. Uterus is connected to the vagina by cervix.

FALLOPIAN TUBES / OVIDUCT:

FEMALE REPRODUCTIVE SYSTEM Fallopian tubes or oviduct carry egg from ovaries to

the uterus.VAGINA : It is the muscular tube like structure in which uterus

opens. Vagina opens to the outside next to the opening of urethra. Both openings are protected by folds of skin called LABIA. Labia protects a small pea size called CLITORIS. This region has large number of receptors like glans penis. Vagina is the root for menstrual blood flow. It is the path way for the sperms to enter inside women’s body. During the process of child birth the baby comes out of the mother’s body through vagina.

MENSTRUAL CYCLE

MENSTRUAL CYCLE This occurs from the beginning of Puberty.It occurs approximately every month in

females. It does not occur when the female is pregnant.

A mature women releases a ovum every month.

This ovum passes from the oviduct to the uterus. If ,on its way it is fertilized then it forms foetus.

But when the ovum is not fertilized it is thrown out of the body through vagina along with the blood and the mucus.

This blood and mucus flow lasts about 3-4 days in every month.

MENSTRUAL CYCLE This causes menstruation.The length of time of period of bleeding

varies between girls and also amount of blood released.

Some feel pain before the menstruation starts.

This cycle continues until the beginning of menopause which may start at about the age of 45.

During the menopause menstrual cycle may become irregular and eventually stop.

SEXUAL INTERCOURCE Before sexual intercourse, the penis and

vagina ready itself. Penis becomes erect by action of muscles

at the base. Then the blood collects in the spongy tissue making it expand and hard.

The vagina widens itself to ease the passage of penis into it. The lining of vagina secretes a fluid which acts as lubricant and further helps the penis to enter easily.

When penis enters vagina, the male and female make thrusting movements to stimulate sensitive areas of glans penis and clitoris.

SEXUAL INTERCOURCE During intercourse the sperms along with

semen enter into the vagina. The action of releasing semen is called

ejaculation. Usually 3-5ml of semen is ejaculated.

SPERMS AND OVUM

Sperms Ovum Male gametes produced

in the testicles. Sperm production

requires lower temperature than body temperature.

They are stored in seminal vesicles.

Parts of sperm: head, middle part, tail.

It can move with tail.

Female gametes produced in the ovaries.

Production of ovum requires normal body temperature.

They are released every month in puberty.

It cannot move and needs cilia to push for movement.

SPERMS AND OVUM

Sperm Ovum

PATH OF SPERM The sperms do not contain food store to provide

them energy for movement.The get their nourishment from semen secreted

seminal vesicles and prostrate gland as they make their way from testicles to urethra. This food provides with energy to lash its tail like a whip and sperm move forward.

The sperm move through cervix and mucus lining of uterus wall to the oviduct. Millions of them die during 4-6 hours of their journey only a few 1000 can enter into the oviduct.

As the sperms swim along the oviduct only few100 can reach to ovum- their destination.

PATH OF SPERM The sperm may survive for 2-3 days before

they die. During this time if sperm meet an egg fertilization may occur.

MOVEMENT OF THE OVUM The ovum has its own food storage. This

food provides energy and materials for early development of the embryo if the ovum is fertilized.

This is the reason for ovum being much larger than the sperm.

It does not move by itself. It is moved by the action of cilia in the wall of oviduct.

Cilia moves forward and backward and push the ovum.

FERTILIZATION When the sperms reach to an ovum in the oviduct

they crowd around it. The head of only one sperm penetrates the cell membrane of the ovum. Then the sperm’s head breaks off from the tail and moves through ovum’s cytoplasm to the nucleus. When the head reaches the nucleus fertilization takes place, the head fuses with the nucleus ,this fertilized cell is called ZYGOTE.

Changes to the cell memebrane around the zygote prevent other sperm head entering and fusing with the nucleus. This zygote contain instructions for the development of the baby. Zygote implants on the uterus wall and can develop into baby

FERTILIZATIONPregnancy: the period of time from

fertilization or conception to the birth of the baby.

DEVELOPMENT OF A BABYAfter fertilization the zygote divides into 2

cells then 4 and so on. It does not increase in size in first 7 days. The cells become smaller and smaller at each division. After 7 days the cells look like a hallow ball, this ball reaches the uterus and sinks into the thick lining of the uterus walls.

The process of sinking the zygote into the uterus wall is called implantation.

THE PLACENTA The cells on the surface of hallow ball cells of the zygote will

form placenta. FUNCTIONS OF PLACENTA :It takes in food and oxygen from mothers blood and supplies

to the cells of zygote so that it can grow and divide. Waste products such as carbon dioxide formed due to cells

activity pass across placenta to the mothers blood for elimination.

It separates baby’s blood and mother’s blood.It makes harmones that stop the overies from producing any

more ovum and stop the uterus wall to break as in normal menstrual cycle.

Antibodies pass from mother’s blood to the baby to protect against diseases.

THE PLACENTA

EMBRYO AND FOETUSThe placenta forms from the cells on the

surface of hollow ball of zygote, while embryo is formed from the cells inside of the hallow ball.

At the end of the first 2 weeks the development of embryo is like a flat disc. After 4 weeks, embryo develops into a simple body shape with stumps where the limbs will grow.

Internally the heart starts beating. By 8 weeks all the organ systems have developed and the embryo is 2.5 cm long. This embryo after 8 weeks is called foetus. By the end of 14 weeks the sex of the foetus can be reveled by ultra sound scan.

EMBRYO AND FOETUSAt about 16 weeks the foetus starts its

movement, it is about 10 cm long. By end of 20 weeks it is 12.5 cm long. Legs are growing quickly.

By end of 28 weeks the foetus turns upside down with its head over the cervix, the alveoli in its lungs begin to grow and continue to grow after birth.

By end of 38 weeks the foetus is about 50 cm long and has mass about 3 kg, the baby is ready born.

Gestation period: length of time during fertilization and birth. It is about 40 weeks.

EMBRYO AND FOETUS

AMNION AND AMNIONTIC FLUID A bag formed around the foetus during the

development is called amnion. The watery fluid inside amnion is called

amniotic fluid.This fluid acts like a cushion around the

foetus and protects it from pressures outside the uterus.

It allows the foetus to float freely so that the growing limbs have space to develop.

BIRTH

BIRTHThere are three stages of birth process First stage : the muscles in the uterus wall begin to

contract. The time between successive contractions is 30 minutes at first. Then it reduces to 2-3 minutes. At some point during contraction, amnion breaks and amniotic fluid passes down through vagina, this is called breaking of waters. At the end the cervix widens, enabling the head of the foetus to come out.

Second stage : the mother contracts her abdominal with contractions of the uterus, to push the foetus down the birth canal. This stage may last up to few minutes and is completed when the baby is born. The umbilical cord is cut and clamped to prevent loss of blood.

BIRTHLABOUR: THE TWO STAGES FROM THE

FIRST CONTRACTIONS OF THE UTERS TO THE BIRTH OF THE BABY.

Third stage : it lasts for about 20 minutes after the second. During this time the placenta comes away from the walls of uterus, and passes down the vagina. When it has left the mother , the placenta is called after birth.

TWINS Non- Identical Twins

Identical Twins

They are dizygotic twins.

They are formed from two different fertilized eggs.

Two different sperms fertilize two different eggs.

They have different genetic material.

They are monozygotic twins.

They are formed from same fertilized eggs.

One sperms fertilize one eggs and divides into 2 to form 2 different embryo.

They have same genetic material.

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