Bladder function after spinal cord injury
The urinary system and its role
The urinary system includes the kidneys, ureters, bladder, sphincter muscles, and the urethra. The purpose of the urinary system is to remove waste from the blood in the form of urine. The urinary system consists of:
- Kidneys: There are two kidneys, one on either side of the body. Blood flows to the kidneys and combines the waste and water to make urine.
- Ureters: There is a ureter that connects each kidney to the bladder. It allows the urine to flow into the bladder.
- Bladder: The bladder collects and holds the urine until it is time to urinate. It stretches when it is full and shrinks when it is empty.
- Sphincter muscles: The sphincters are two muscles in the bladder which close to keep the urine in the bladder as well as open to let the urine out of the bladder.
- Urethra: The urethra is a muscular tube leading from the bladder to the outside of the body. This is the exit point for urine outside the body.
How the bladder normally works
Normally, the bladder empties through the process of urination when the brain sends messages through the spinal cord telling the bladder to contract so the sphincter muscles will open. When the sphincter opens, the bladder drains. A spinal cord injury (SCI) interferes with this process.