Human Reproduction and Reproductive Health

7.3.2 Reproduction in Human Beings

Human beings reproduce sexually. A mature male produces sperms, a mature female produces eggs; fertilisation of an egg by a sperm produces a zygote that develops inside the mother into a new human. The reproductive system becomes functional after puberty — the set of physical and emotional changes that convert a child's body into an adult one.

Male Reproductive System

The main organs are the pair of testes, housed in a pouch of skin called the scrotum, which lies outside the abdominal cavity. Why outside? Because the formation of healthy sperms requires a temperature 2–3 °C lower than normal body temperature. The testes perform two jobs:

• Produce the male hormone testosterone, which drives the changes of puberty and sperm production.
• Produce sperms — tiny, motile cells with a head carrying DNA and a long tail for swimming.

Sperms travel from the testis through a storage tube called the epididymis, then through the vas deferens. On the way they are mixed with fluids from the seminal vesicles and the prostate gland. These fluids nourish the sperms, keep them alive and help them swim. The mixture of sperms and fluids is called semen. It leaves the body through the urethra, a tube that runs through the penis and also carries urine at other times.

Female Reproductive System

The main organs are a pair of ovaries, one on each side of the lower abdomen. Each ovary at birth already contains thousands of immature eggs. After puberty, one ovary releases one mature egg each month — this event is called ovulation. The ovaries also secrete the female hormones oestrogen and progesterone, which regulate the menstrual cycle and development of secondary sexual characters.

The released egg is picked up by the funnel of the fallopian tube (oviduct). It is here, in the upper part of the fallopian tube, that fertilisation occurs if sperms are present. The fertilised egg then travels down to the uterus (womb) — a muscular, pear-shaped organ where the baby will grow for nine months. The lower, narrow end of the uterus opens into the vagina, the birth canal through which the baby is delivered.

Puberty Changes

Secondary sexual characters distinguish adult males from adult females but are not directly part of reproduction. In boys, voice deepens, facial hair appears and shoulders broaden. In girls, breasts develop, hips widen and menstruation begins. Both experience growth spurts, appearance of under-arm and pubic hair, acne and emotional changes. All of these are natural and normal.

7.3.3 What Happens When the Egg Is NOT Fertilised?

Every month the uterus prepares a thick, blood-rich lining called the endometrium in case a fertilised egg arrives. If fertilisation does not happen within a day or two of ovulation, the prepared lining is not needed. It breaks down and flows out of the body through the vagina, along with some blood. This monthly flow, lasting 3–5 days, is called menstruation (periods).

A full menstrual cycle lasts about 28 days and has four overlapping phases:

7.3.4 What Happens When the Egg IS Fertilised?

If sperms are present in the fallopian tube at the time of ovulation, one sperm may fuse with the egg. The fertilised cell — the zygote — immediately begins to divide. By the time it reaches the uterus a few days later, it has become a small ball of cells called an embryo. The embryo implants itself into the thick uterine lining. Once implanted, a special structure called the placenta develops. The placenta is connected to the embryo through the umbilical cord.

The placenta is the embryo's lifeline:

• Nutrients and oxygen pass from the mother's blood into the embryo's blood.
• Waste products like carbon dioxide and urea pass from the embryo back to the mother for disposal.
• Importantly, mother's and baby's blood do not mix directly; exchange happens across a thin membrane.

The embryo gradually develops into a foetus with recognisable organs. Total pregnancy (gestation) in humans is about nine months. At the end of this period, strong contractions of the uterine muscles push the baby out through the vagina — childbirth (parturition).

7.3.5 Reproductive Health

Good reproductive health means more than just avoiding disease — it means a complete state of physical, mental and social well-being in all matters relating to the reproductive system. Topics of special importance in Class 10 are sexually transmitted infections, contraception and family planning, and the serious social issue of prenatal sex determination.

Sexually Transmitted Diseases (STDs)

Certain diseases spread from one person to another through sexual contact. Bacterial examples include gonorrhoea and syphilis; viral examples include HIV/AIDS and warts. Some — like AIDS — have no permanent cure. Protection (such as using condoms) and awareness are the best defences.

Contraception — Preventing Unwanted Pregnancy

Contraception allows couples to plan if and when to have children. The common methods are grouped as:

Family Planning and Maternal-Child Care

Small, well-spaced families allow parents to provide better nutrition, education and care to each child. Mothers also need adequate gap between pregnancies to recover. Good antenatal check-ups, balanced diet, vaccination and mental support are equally important for both the mother and the developing child.

Prenatal Sex Determination — Illegal in India

Biologically, a baby's sex is decided purely by which sperm (X or Y chromosome bearing) fertilises the egg. The mother has no role in determining the sex of the child. Social prejudice against daughters is therefore based on ignorance and injustice.