Reproduction may be defined as the production of new generation of individuals of the same species that are physically independent of their parents. Organisms reproduce to increase in number. All the members produced from the parents look like parents as well as they look very much like themselves. Thus, reproduction results in the increase of members which look alike. The organisms which look similar to each other belong to the same species.
Reproduction is an energy spending process which is not essential to maintain the life of an individual organism, as nutrition, respiration, excretion are the most essential life processes in the body. If one of the above life processes stop performing, then a man can not survive. But reproduction is the choice of someone else in order to increase in number. It provides group immortality by replacing the dead individuals with new ones for the survival of the species on this earth.
During copulation, the human male inserts his penis into the vagina of the female and releases gametes (Sperms) inside the genetial tract. Then, they travel upwards as they are small and motile and reach the oviduct where they may encounter the egg. After the fusion of gametes take place, Zygote (fertilised egg) starts dividing to form a ball ofbcells or embryo. It is implanted in the lining of the uterus where they continue to grow and develop organs to become foetus. The uterus prepares itself every month to receive and nuture the growing embryo. The embryo gets nutrition from the mother's blood with the help of a special tissue called placenta.
Placenta is a disc which is embedded in the uterine wall and contains villi on the embryo's side of the tissue and spaces on mother's side which surround the villi. This provides a large surface area for glucose and oxygen to pass from the mother to the embryo. Placenta allows nutrition uptake, thermo-regulation, Waste-elimination and Gas Exchange via the mother's blood supply.
The complete development of foetus, from the intial stage of conception till the birth of the young one, is called gestation. It takes 9 months for complete developmentIf, however, the egg is not fertilised, It lives for about one day. As ovary releases one egg every month, The uterus prepares itself every month to receive fertilised egg so that it's lining becomes thick and spongy. This would be required for nourishing the embryo, If fertilisation takes place. If fertilisation is not done, Then the lining is not needed any longer. Hence, It slowly breaks and comes out through vagina as blood and mucous. This cycle, is what we say as menstruation which lasts for about two to eight days.
Reproduction is an energy spending process which is not essential to maintain the life of an individual organism, as nutrition, respiration, excretion are the most essential life processes in the body. If one of the above life processes stop performing, then a man can not survive. But reproduction is the choice of someone else in order to increase in number. It provides group immortality by replacing the dead individuals with new ones for the survival of the species on this earth.
During copulation, the human male inserts his penis into the vagina of the female and releases gametes (Sperms) inside the genetial tract. Then, they travel upwards as they are small and motile and reach the oviduct where they may encounter the egg. After the fusion of gametes take place, Zygote (fertilised egg) starts dividing to form a ball ofbcells or embryo. It is implanted in the lining of the uterus where they continue to grow and develop organs to become foetus. The uterus prepares itself every month to receive and nuture the growing embryo. The embryo gets nutrition from the mother's blood with the help of a special tissue called placenta.
Placenta is a disc which is embedded in the uterine wall and contains villi on the embryo's side of the tissue and spaces on mother's side which surround the villi. This provides a large surface area for glucose and oxygen to pass from the mother to the embryo. Placenta allows nutrition uptake, thermo-regulation, Waste-elimination and Gas Exchange via the mother's blood supply.
The complete development of foetus, from the intial stage of conception till the birth of the young one, is called gestation. It takes 9 months for complete developmentIf, however, the egg is not fertilised, It lives for about one day. As ovary releases one egg every month, The uterus prepares itself every month to receive fertilised egg so that it's lining becomes thick and spongy. This would be required for nourishing the embryo, If fertilisation takes place. If fertilisation is not done, Then the lining is not needed any longer. Hence, It slowly breaks and comes out through vagina as blood and mucous. This cycle, is what we say as menstruation which lasts for about two to eight days.