Question

Explain reproduction in human beings ?

Answer 1

Sexual reproduction is the formation of a new individual following the union of two gametes. In humans and the majority of other eukaryotes - plants as well as animals - the two gametes.

The reproductive system of the male has two major functions:

1. Production of sperm
2. Delivery of these to the reproductive tract of the female.

The responsibility of the female mammal for successful reproduction is considerably greater than that of the male.Functions are:

1. Manufacture eggs
2. Be equipped to receive sperm from the male
3. Provide an environment conducive to fertilization and implantation
4. Nourish the developing baby not only before birth but after.

Copulation and Fertilization:

For fertilization to occur, sperm must be deposited in the vagina within a few (5) days before or on the day of ovulation. Sperm transfer is accomplished by copulation. Sexual excitation dilates the arterioles supplying blood to the penis. Blood accumulates in three cylindrical spongy sinuses that run lengthwise through the penis. The resulting pressure causes the penis to enlarge and erect and thus able to penetrate the vagina.
Movement of the penis back and forth within the vagina causes sexual tension to increase to the point of ejaculation. Contraction of the walls of each vas deferens propels the sperm along. Fluid is added to the sperm by the seminal vesicles, Cowper's glands, and the prostate gland.These fluids provide
a source of energy (fructose) an alkaline environment to activate the sperm, and perhaps in other ways provide an optimum chemical environment for them.
The mixture of sperm and accessory fluids is called semen. It passes through the urethra and is expelled into the vagina.Once deposited within the vagina, the sperm proceed on their journey into and through the uterus and on up into the fallopian tubes. It is here that fertilization may occur if an "egg" is present.

Pregnancy:

Development begins while the fertilized egg is still within the fallopian tube. Repeated mitotic divisions produces a solid ball of cells called a morula. Further mitosis and some migration of cells converts this into a hollow ball of cells called the blastocyst. Approximately one week after fertilization, the blastocyst embeds itself in the thickened wall of the uterus, a process called implantation, and pregnancy is established.