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Control of Urination

By

Patrick J. Shenot

, MD, Sidney Kimmel Medical College at Thomas Jefferson University

Last full review/revision Apr 2020| Content last modified Apr 2020
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The kidneys constantly produce urine, which flows through two tubes (the ureters) to the bladder, where urine is stored (see Figure: Viewing the Urinary Tract). The lowest part of the bladder (the neck) is encircled by a muscle (the urinary sphincter) that remains contracted to close off the channel that carries urine out of the body (the urethra), so that urine is retained in the bladder until it is full.

When the bladder is full, messages travel along nerves from the bladder to the spinal cord. The messages are then relayed to the brain, and the person becomes aware of the urge to urinate. A person who has control of urination can consciously and voluntarily decide whether to release the urine from the bladder or to hold it for a while. When the decision is made to urinate, the sphincter muscle relaxes, allowing urine to flow out through the urethra, and the bladder wall muscles contract to push the urine out. Muscles in the abdominal wall and floor of the pelvis can be contracted voluntarily to increase the pressure on the bladder.

A variety of disorders can interfere with the control of urination, among them

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Nephrotic Syndrome
Glomeruli are clusters of tiny blood vessels in the kidneys containing pores that filter blood. In patients with nephrotic syndrome the glomeruli do not function properly and cause excessive protein excretion into the urine. Excessive protein excretion in turn may lead to fluid accumulation, low levels of the protein albumin in the blood, and high levels of blood fats. There are several causes of nephrotic syndrome, including which of the following?
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