REPRODUCTIVE SYSTEM

The female reproductive system consists of the uterus, fallopian tubes, ovaries and external genitalia. Although the reproductive system's primary function is the bearing of children, the sex hormones produced by the ovaries also play crucial roles in maintaining bone density and in the growth, maintenance and repair of the reproductive tissues.

The visible external portion of the reproductive system in women consists of two fleshy outer folds of skin (the labia majora or greater lips) and within those, two smaller, thinner folds (the labia minora or lesser lips). These structures offer some protection to the delicate and sensitive tissues beyond them. Most sensitive of all is the clitoris, a small node of erectile tissue that stiffens during sexual arousal much as the penis does in males. The clitoris is situated where the folds of the labia meet in the front. The labia guard the opening of the urinary tract (the urethral meatus, the entrance to the urethra, which leads to the bladder) as well as the vagina, a canal approximately 5 inches. long with muscular walls. The uterus lies at the inner most recess of the vagina. The lower end of the uterus, the cervix, protrudes into the vaginal vault.

The uterus is a small (about 2.5 to 3 inches in the nonpregnant state), hollow organ shaped like an upside-down pear. Its thick muscular walls are powerful enough to expel the fetus during childbirth.

On either side of the uterus, the fallopian tubes, a pair of slender hollow tubes, extend outward, draping their fringe-like ends near the ovaries to gather in the eggs released with each monthly reproductive cycle. Despite their tiny size, only about 1 inch long, the ovaries at birth contain about 1 million dormant eggs, a number sufficient to last a reproductive lifetime.

>Internal Anatomy
>Female Sexual Response
>Abnormalities
>Female Reproductive Problems

The male reproductive and urinary systems are more intimately related than the female systems. Problems affecting one system tend to affect the other. In fact, the same medical/surgical specialist, the urologist, cares for both urinary and reproductive system problems in men.

The male genital organs include the testicles, vas deferens, seminal vesicles, prostate gland and the penis, which is both a sexual organ and a urinary tract organ because the urethra (urine tube) runs lengthwise through its center.
The penis consists of a body or shaft of erectile tissue, and an expanded head, called the glans penis, covered at birth with a redundancy of skin, called the foreskin, from which it emerges when erect and into which it retracts when flaccid (soft). The urethra runs along the underside of the penis, providing a passageway for both urine from the bladder and for semen during ejaculation. The body of the penis is composed of three rod-shaped structures made of a spongy network of interconnected blood vessels with some smooth muscle tissue.

The ability to have and maintain a penile erection requires normally functioning nerves to the area, an unobstructed blood supply, and normal male hormonal levels. Penile erection occurs primarily as a result of psychological and emotional factors accompanying sexual arousal, although direct stimulation of the penis can cause or contribute to the erection through local reflexes. As a result of sexual arousal, the brain and central nervous system cause the release of several neurotransmitters in the penis. The most important neurotransmitter is nitric oxide, a substance closely related to nitrous oxide (laughing gas). In response to these neurotransmitters, blood vessels in the penis dilate so that the spongy tissue of the erectile bodies becomes engorged, causing the penis to straighten and stiffen.

>Male Reproductive Organs
>Reproductive System
>Male Sexual Response
>Male Reproductive Problems