Read the information about human reproduction. Get ready to comment the text

HUMAN REPRODUCTION

Human reproduction is the pro­cess by which human beings create more of their own kind. A new individual develops from the joining together of two sex cells, one from a female parent and one from a male parent. The union of these cells is called fertilization.

Biologists refer to sex cells as gametes. Females produce gametes called eggs or ova. Male gametes are called sperm. Fertilization may oc­cur after a male delivers sperm to the female's egg by means of sexual intercourse. Fertilization begins a remarkable period of development in which the egg develops into a fully formed baby within the body of the female. This period of development, called pregnancy, takes about nine months.

At the beginning of pregnancy, the fertilized egg is smaller than the period at the end of this sentence. The egg develops into a growing mass of cells called an embryo. Gradually, the cells rearrange themselves to form tissues. By the end of the second month of pregnancy, all the major body organs and organ systems have formed and the embryo looks distinctly human. During the rest of pregnancy, the embryo is called a fetus. The fetus grows while its systems prepare for the day when they must function outside the mother's body. Pregnancy ends when the new baby passes out of the mother's body at birth.

Human beings are born with the body organs needed for reproduction. But reproduction cannot actually occur until these organs mature. This maturation pro­cess takes place during puberty, a period of several years in which a boy or girl goes through dramatic physical changes. These changes are regulated by certain hormones (chemicals produced by the body). Puberty begins during or just before the early teen-age years.

The reproductive systems of females and males differ greatly in shape and structure. But both systems are specifically designed to produce, nourish, and trans­port the eggs or sperm.

III. Post-reading activities.

Answer the following questions.

1.How do we call the process by which human beings create more of their awn kind?

2. How do we call the union of female and male sex cells?

3. What gametes does a female produce?

4. How are male gametes called?

5. When may fertilization occur?

6. How many months does pregnancy take? When does pregnancy end?

7. Are human beings born with the body organs needed for reproduction?

8. When does maturation process take place?

9. What is the function of the reproductive systems of females and males?

Поиск по сайту: