Urinary Tract The body stores urine—water and wastes removed by the kidneys—in the bladder, a balloon-like organ. The bladder connects to the urethra, the tube through which urine leaves the body. During urination, muscles in the wall of the bladder contract, forcing urine out of the bladder and into the urethra. At the same time, sphincter muscles surrounding the urethra relax, letting urine pass out of the body.
Digestive Tract In the digestive tract, muscles propel food and liquid along in a wave-like movement called peristalsis. The lowest part of the colon is connected to the rectum where feces (waste products) from digested food are stored. As the feces fill the rectum, the walls expand and nerve receptors stimulate the urge to defecate (have a bowel movement). Muscles in the rectum push the feces into the anal canal, where internal and external sphincter muscles relax and allow the feces to be expelled.
Female Reproductive Organs The uterus is located in the lower abdomen between the bladder and the rectum. The uterus is also called the womb. It is pear-shaped, and the lower, narrow end of the uterus is the cervix. When a woman is pregnant, the baby grows in the uterus until he or she is born. On each side of the uterus at the top are the fallopian tubes and ovaries. Together, the uterus, vagina, ovaries, and fallopian tubes make up the reproductive system.
Pelvic FloorAt the bottom of the pelvis, several layers of muscle and tissues stretch between your legs, called the pelvic floor. The muscles attach to the front, back, and sides of the pelvis bone. Two pelvic muscles do most of the work. The largest one stretches like a hammock. The other is shaped like a triangle. These muscles help keep the pelvic organs supported in place and functioning properly.