Reproductive System
From Halbeeg, the open encyclopedia · Af-Soomaali
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The reproductive system is a group of bodily organs whose primary function is to produce reproductive cells (gametes) and, in some organisms, to nurture and develop the fetus. It is the only system that an individual does not need for their own survival, but the species as a whole requires it to continue.
In humans and other mammals, this system differs between male and female. Both sexes produce reproductive cells (gametes): females produce ova (eggs), while males produce sperm. Their fusion, called fertilization, creates a zygote, which begins the development of the fetus.
Female reproductive organs
The most important organs are the ovaries, fallopian tubes, uterus, cervix, and vagina. The ovaries produce ova and hormones such as estrogen and progesterone. Fertilization typically occurs in the fallopian tube, after which the fetus implants in the wall of the uterus. The uterus nurtures the fetus during pregnancy. The breasts, though not internal reproductive organs, are involved in nursing the infant after birth.
Male reproductive organs
These include the testes, located in the scrotum, a small pouch that maintains the proper temperature for sperm production; ducts such as the epididymis and vas deferens; and glands attached to the urethra such as the prostate and seminal vesicles. The testes produce sperm and the hormone testosterone. The penis serves to deliver semen.
Hormonal control
The reproductive system operates under signals from the brain: the hypothalamus produces GnRH, which stimulates the pituitary gland to release FSH and LH. These hormones signal the ovaries or testes to produce reproductive cells and hormones. This system has a feedback mechanism that regulates hormone levels. In females, the regular cycle is based on monthly fluctuations of these hormones.
Development and variation in life forms
Reproductive organs begin their full function at puberty, when hormone levels rise. Other organisms have different reproductive systems: fish and amphibians typically have external fertilization, birds lay eggs, and plants have reproductive organs located in flowers. Some organisms reproduce asexually, without the combination of male and female elements.