How the Bladder Works
The bladder collects urine from the ureters which are muscular tubes that lead from the kidneys.
Normally, the bladder holds about a cup or more of urine at its maximum capacity. The bladder is
mostly muscle. and must be relaxed in order to allow urine to accumulate there.
Normally, the bladder holds about a cup or more of urine at its maximum capacity. The bladder is
mostly muscle. and must be relaxed in order to allow urine to accumulate there.
The urethra is a tube that delivers urine from
the bladder to outside the body. It exits from
the area of the vaginal opening near the
pubic bone. It has two areas, one made up of
voluntary muscles (those you can control) and
one made up of involuntary muscles (those
you cannot control).
the bladder to outside the body. It exits from
the area of the vaginal opening near the
pubic bone. It has two areas, one made up of
voluntary muscles (those you can control) and
one made up of involuntary muscles (those
you cannot control).
The bladder neck is made up of a highly
specialized muscle that prevents urine from
leaking from the bladder, and so must be in a
state of tension to keep urine inside the bladder.
specialized muscle that prevents urine from
leaking from the bladder, and so must be in a
state of tension to keep urine inside the bladder.
Therefore, in order to keep urine inside the
bladder, or maintain "continence", the bladder
itself must be relaxed and the urinary sphincter
or bladder neck must be contracted. Very
specific nerves maintain contraction and
relaxation.
bladder, or maintain "continence", the bladder
itself must be relaxed and the urinary sphincter
or bladder neck must be contracted. Very
specific nerves maintain contraction and
relaxation.
In order to urinate, the urge to void stimulates
part of the brain. Conscious relaxation of the
external sphincter by sitting on the toilet and
"allowing" yourself to void, stimulates the
bladder muscle itself to contract, and the
internal sphincter to relax. Then voiding
occurs.
part of the brain. Conscious relaxation of the
external sphincter by sitting on the toilet and
"allowing" yourself to void, stimulates the
bladder muscle itself to contract, and the
internal sphincter to relax. Then voiding
occurs.
Internal Sphincter
External sphincter
 |  |  |  |  |  |  |