Organ: Urinary tract
Introduction: Urination, or voiding, is a complex activity. The bladder is a balloonlike muscle that lies in the lowest part of the abdomen. The bladder stores urine, then releases it through the urethra, the canal that carries urine to the outside of the body. Controlling this activity involves nerves, muscles, the spinal cord, and the brain.
The bladder is made of two types of muscles: the detrusor, a muscular sac that stores urine and squeezes to empty, and the sphincter, a circular group of muscles at the bottom or neck of the bladder that automatically stay contracted to hold the urine in and automatically relax when the detrusor contracts to let the urine into the urethra. A third group of muscles below the bladder (pelvic floor muscles) can contract to keep urine back.
A baby's bladder fills to a set point, then automatically contracts and empties. As the child gets older, the nervous system develops. The child's brain begins to get messages from the filling bladder and begins to send messages to the bladder to keep it from automatically emptying until the child decides it is the time and place to void.1
The system that takes wastes from the blood and carries them out of the body in the form of urine. The urinary tract includes the kidneys, renal pelvises, ureters, bladder, and urethra. 2
The organs, tubes, muscles, and nerves that work together to create, store, and carry urine are the urinary system. The urinary system includes two kidneys, two ureters, the bladder, two sphincter muscles, and the urethra. 3
The urinary tract, or system, consists of the kidneys, ureters, bladder, and urethra. The kidneys are two bean-shaped organs located below the ribs toward the middle of the back. The kidneys remove extra water and wastes from the blood, converting it to urine. They also keep a stable balance of salts and other substances in the blood. The kidneys produce hormones that help form red blood cells. 4
Condition count: 32 ; see list below.
Organ subtypes: bladder (24), urethra (4), ureter (4)
Related organs: sex organs (138), female sex organs (97), male sex organs (50)
Main condition: Urinary disorders
Organs: all organs
Diseases list: The following list of medical conditions have 'Urinary tract' or similar listed as an affected body part in our database:
1. excerpt from Urinary Incontinence in Children: NIDDK
2. excerpt from Kidney Failure Glossary: NIDDK
3. excerpt from Your Urinary System and How It Works: NIDDK
4. excerpt from Kidney Diseases: NWHIC
Medical Tools & Articles:
- Risk Factor Center
- Medical Statistics Center
- Medical Treatment Center
- Prevention Center
- Medical Tests Center