Saturday, May 5, 2012

How does a baby develop?

We have discussed both male and female reproductive systems through the past two posts. Also, some scientific understanding about how we are born to this world will be very useful to all of us. Even today, many people have groundless misconceptions about this matter, while we can discuss separately. Now, let us see how modern science can explain this matter to us.
The male and female reproductive systems allow humans to produce children. Sexually intercourse or making love is a very intimate and pleasurable act between a man and a woman. In this process, man’s semen containing sperms passes out of the end of his penis and centers the woman’s reproductive system through her vagina. So, a new human life begins when a male sperm joins a female egg (or ovum) in the fallopian tube of a woman. This process is called fertilization.
We already know that sperms and eggs are the living reproductive cells produce by males and females. Actually, for fertilization, sperm must swim through the cervix, through the uterus (womb) and along the fallopian tube. Then sperms must meet an egg, which is travelling in the opposite direction along the fallopian tube. One sperm must enter the egg and both these cells must join together.
When a sperm meets an egg, their nuclei (the central parts of the two living cells) fuse. This fusion (or becoming joined) means that a “new” cell is produced, which combines genetic information (half from each) from the father and the mother. This single cell (called a zygote) divides again and again to foam a ball of cell (called an embryo), which eventually travels from the fallopian tube and become attached to the lining of the uterus (womb) a process called implantation.
The embryo also releases hormones, which prevents the normal procedures of the menstrual cycle and stabilizes conditions inside the womb until birth. Because of this pregnant woman will not have menstruation, and hormones will also be present in her urine, which is the basis of most pregnancy tests.
In the womb, part of the embryo develops into a structure called the placenta, and a flexible tube of tissue called the umbilical cord connects the placenta to the navel of the embryo. Also, the embryo is protected in a bag of liquid (water bag) called the amnion.
The placenta has an important role in supplying everything that the developing embryo needs, and removing what it does not need, through the umbilical cord. All these substances are supplied and removed by the mother’s blood circulation system working together with the baby’s own blood system. However, the mother’s and the baby’s blood do not mix though they come into close contact in the placenta.
Moreover, as time goes by the embryo develops with noticeable human features, and this developing baby is called a foetus.  After two weeks of fertilization, blood cells start to form in the foetus (or embryo) and the heart begins to beat after four weeks. At eight weeks, the foetus is about four centimeter long and has the entire major organ even though it is small. As the foetus grows, the mother’s womb expands and extends above the level of the navel, and this enlargement of the womb pushes her abdominal organ upwards. Eventually the foetus ends up in head downward position, and the baby is ready to be born after nine months.
Then, the muscles of the womb start to contract repeatedly, causing labour and pushing the baby out of the uterus (womb), through the cervix and down the vagina. The water bag bursts and the baby comes out, still attached by the umbilical cord and placenta to the mother’s body systems. When the newborn baby begins to breathe air, the umbilical cord is clamped and cut, and the placenta also is expelled from the womb.


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