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The Urinary System is made up of five major parts:
 The
Kidneys: The two kidneys filter waste and excess
water from the blood and produce urine. Urine is being produced
every minute of the day.
The Ureters: Each kidney
has a thin, hollow tube that connects to the bladder. Urine
flows down the ureters from the kidneys and empties into the
bladder. The ureters have one-way valves in them, so even if you
were to stand on your head, urine could not flow back to the
kidneys from the bladder.
The Bladder: The bladder
is a collapsible sac lying in the pelvis. It is able to stretch
to hold urine until you are ready to urinate. The bladder walls
are made up of muscles known collectively as the detrusor
muscles. When you are ready to urinate, the detrusor muscles
contract (squeeze) to help push the urine from the bladder. The
lower portion of the bladder, which funnels urine into the
urethra, is called the bladder neck or bladder outlet.
The Sphincter Muscles:
The internal and external sphincter muscles form a ring around
the urethra to keep urine in the bladder. When you are ready to
urinate, these muscles relax to allow urine to flow out of the
bladder.
The Urethra: The urethra
is a small tube that allows urine to flow from the bladder to
outside the body. The male urethra is 8-10 inches long and the
female urethra is 1-2 inches long. The external urethral opening
from the body is called the meatus for both men and women.
Voiding (Urination)
Normally, when the bladder become full (about 1-2 cups or
400-500ml for most people), nerve endings in the bladder wall
send a message to the brain via the spinal cord. The brain sends
a message back to the bladder to contract the detrusor muscles
and relax the sphincter muscles so you can void. If you can't
get to a toilet, the brain delays the messages until you are
ready to void.
After a Spinal Cord Injury
The bladder, along with the rest of the body, undergoes
dramatic changes. Since messages between the bladder and the
brain cannot travel up and down the spinal cord, the voiding
pattern described above is not possible. Depending on your type
of spinal cord injury, your bladder may become either "floppy"
(flaccid) or "hyperactive" (spastic or reflex).
The Flaccid Bladder: A floppy bladder loses detrusor muscle tone (strength) and does
not contract for emptying. This type of bladder can be easily
overstretched with too much urine, which can damage the bladder
wall and increase the risk of infection.
Emptying the flaccid bladder can be done with techniques such as
Crede, Valsalva, or intermittent catheterization. It is very
important that you do not let your bladder get overfull, even if
it means waking up at night to catheterize yourself more
frequently.
The Reflex Bladder: The detrusor muscles in a hyperactive bladder may have increased
tone, and may contract automatically, causing incontinence
(accidental voiding). Sometimes the bladder sphincters do not
coordinate properly with the detrusor muscles, and medication or
surgery may be helpful.
Bladder Management after
SCI -
Urinary Tract Infections -
Spinal Injury
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