Sexual reproduction in humans

You must have observed that when a child is small, it becomes difficult to distinguish from appearance whether the child is a boy or a girl.

But as we grow, changes start taking place in the body. These changes have been summarised below:

The period during which adolescent boys and girls reach sexual maturity and become capable of reproduction is called puberty.

Let us now look at Male Reproductive System.

The male reproductive system consists of parts that make the germ cells, and parts that deliver them to the site of fertilization.

The male sex-cells are sperms, that are tiny bodies that consist of mainly genetic material and a long tail that helps them to move towards the female germ-cell.

1. The formation of germ cells or sperms takes place in testes, which are located outside the abdominal cavity in scrotum.
2. The sperms formed are delivered through the vas deferens.
3. Along this path, glands like the prostate and the seminal vesicles add their secretions to provide the sperms a fluid medium to travel.

Female Reproductive System –

1. The female germ-cells are made in the ovaries. After maturation,one egg is produced every month by one of the ovaries.
2. The egg is carried from the ovary to the womb through the fallopian tube.
3. The two oviducts unite into the uterus.
4. The uterus opens into the vagina through the cervix.

Let us now study how fertilisation takes place.

For fertilization to happen, male egg has to fuse with female egg cell. This is done in the following manner:

1. The sperms from the male enter through the vaginal passage during sexual intercourse.
2. They travel upwards and reach the oviduct where they may encounter the egg.
3. The cells fuse together, and the fertilised egg, the zygote, gets implanted in the lining of the uterus, and starts dividing.
4. The embryo gets nutrition from the mother’s blood with the help of a special tissue called placenta. It provides a large surface area for glucose and oxygen to pass from the mother to the embryo and waste substances to pass from embryo to mother.
5. The child develops inside mother’s body and is born as a result of rhythmic contractions of the muscles in the uterus.

Now, have you wondered what happens if fertilization does not take place!?

We saw that the ovary releases one egg every month. Thus, the uterus also prepares itself every month to receive a fertilised egg. Its lining becomes thick and spongy for this purpose.

This would be required for nourishing the embryo if fertilisation had taken place.

Now, however, this lining is not needed any longer. So, the lining slowly breaks and comes out through the vagina as blood and mucous. This cycle takes place roughly every month and is known as menstruation. It usually lasts for about two to eight days.

Reproductive Health

We all know that our country’s population is increasing day by day, and this creates problem as we have a limited number of resources. Therefore, birth control methods are being actively spread today. Not only this, unsafe sexual act can also lead to many diseases, called sexually transmitted diseases. You can now see these and some birth control methods on your screen now.

Sexually Transmitted Diseases (STD):

1. Gonorrhoea  (caused by bacteria)
2. Syphilis (caused by bacteria)
3. AIDS (Acquired Immune Deficiency Syndrome) (caused by virus, HIV)

Birth control methods:

1. Barrier methods – this involves condoms, diaphragms. These devices prevent sperm from meeting the ovum
2. Chemical methods – females can use 2 types of pills – oral pills and vaginal pills. Both of these help in avoiding pregnancy
3. Intra-uterine Contraceptive Devices – example copper-T. It is placed inside woman’s uterus and prevents implantation of fertilized egg in her uterus
4. Surgical methods – in males, this process is called ‘vasectomy’ and involves removal and then tying up a part of vas deferens. In females, it is called ‘tubectomy’ and involves removal and tying up of a small portion of oviducts.