The reproductive system is made up of a group of sexual organs that mark the physical difference between males and females. Human reproduction begins when sperm from the male fertilizes an egg from the female. Reproductive organs become fully functional only when the body has matured and experienced puberty, but the level of the hormones that result in these changes decreases as people become older.
Ovaries, fallopian tubes, the vagina, the uterus and the cervix, located inside the female body, make up the female genital system. The female reproductive system produces eggs, and females are born with ovaries that contain thousands of them. When puberty begins in females, the pituitary gland begins to stimulate the ovaries to produce estrogen. Other functions of the female genital system include receiving sperm, transporting the egg to the site of fertilization, and child birth.
A male's reproductive system includes the penis, testicles, epididymis, and urethra, most of which are found outside of the body. Testicles produce sperm as well as the male hormone testosterone beginning at puberty. Mature males are capable of producing millions of sperm cells daily. Once the testicles have produced sperm the epididymis acts as a storage center.
The egg must be fertilized by sperm for reproduction to take place. A fetus grows within the female's uterus during a 40 week gestation period. The characteristics that children inherit from their parents come from the genetic material contained within both the female's egg and male's sperm.
As a woman ages, many changes in her reproductive system occur. Menopause is a normal process for females and causes the ovaries to stop releasing eggs, ending the woman's ability to reproduce, and ends menstrual periods. Levels of the hormones estrogen, progesterone, estradiol, and testosterone decrease during this period.
Testosterone is an important hormone for the male reproductive system. It allows the development of voice characteristics and stimulates muscle growth. Likewise, without testosterone, men would have no sperm and would not grow facial hair. Males, as well as females, need estrogen to develop sturdy and healthy bones.
The male reproductive system also undergoes changes due to aging. Most of these changes take place in the testes. Levels of testosterone decline with age and reduce sexual desire. Men also experience less blood flow to the penis and thinning of their testicular tissue. Andropause, or the gradual decline of testosterone production, continues as a man ages, however, testosterone production never ceases entirely.