The urinary tract may seem simple, but it is a complicated system made up of several different parts. These parts work together to rid the body of urine, which is excess water and waste. If just one part does not work properly, urine can become backed up, and a kidney, bladder or urinary tract infection can develop. Taking a look at the different parts of the urinary system will give you a new appreciation for the way the body works to keep you healthy.
The first part of the urinary tract is the kidneys, which are located midway down the back, below the rib cage. The kidneys work to filter waste products, which come from the breakdown of body tissues and food, and extra water out of the bloodstream, which becomes urine. According to the National Kidney and Urologic Diseases Information Clearinghouse, the kidneys process approximately 200 qt. of blood daily, producing roughly 2 qt. of urine. The blood comes into the kidneys, where it is filtered by over 1 million nephrons (filtering units). The clean blood is then sent back into the body and the waste-filled urine is sent into the ureters.
The ureters are tiny tubes that run out of the kidneys and down to the bladder. Once the waste is filtered out of the blood and becomes urine, it is sent into the ureters for transport into the bladder. The Ohio State University Medical Center explains that there are muscles in the walls of the ureters that contract and relax, which pushes the urine toward the bladder and away from the kidneys. If these muscles don't function properly, and the urine does not flow away from the kidneys, a kidney infection can result.
While there are two kidneys and two ureters, there is only one bladder, which is located in the lower abdomen, behind the pelvic bone. Urine leaves the ureters and enters the bladder every 10 to 15 seconds, where the bladder holds it until you feel pressure to release the urine. The OSUMC states that the bladder expands its muscular walls to hold up to 2 cups of urine. The bladder also contains nerves, which tell the brain when it is full and urine needs to be voided, and two sphincter muscles. These sphincter muscles are at the bottom of the bladder and stay closed until they relax when it is time to urinate.
When the bladder relaxes and releases urine, it passes into the urethra, which is a tube located at the bottom of the bladder that leads to the outside of the body. According to the Merck Manuals Online Medical Library, the urethra in men is approximately 8 inches long, ending at the head of the penis. In women, it is only 1 1/2 inches long, and ends at the vulva, near the vaginal opening.