- 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.
- How Does the Urinary System Work?
- Your body takes nutrients from food and uses them to maintain
all bodily functions including energy and self-repair. After your body has taken what it
needs from the food, waste products are left behind in the blood and in the bowel. The
urinary system works with the lungs, skin, and intestines--all of which also excrete
wastes--to keep the chemicals and water in your body balanced. Adults eliminate about a
quart and a half of urine each day. The amount depends on many factors, the major ones
being the amount of fluid and foods a person consumes and how much fluid is lost through
sweat and breathing. Certain types of medications can also affect the amount of urine
eliminated.
The urinary system removes a type of waste called urea from
your blood. Urea is produced when foods containing protein, such as meat, poultry, and
certain vegetables, are broken down in the body. Urea is carried in the bloodstream to
the kidneys.
The kidneys are bean-shaped organs about the size of your
fists. They are near the middle of the back, just below the rib cage. The kidneys remove
urea from the blood through tiny filtering units called nephrons. Each nephron consists of
a ball formed of small blood capillaries, called a glomerulus, and a small tube called a
renal tubule. Urea, together with water and other waste substances, forms the urine as it
passes through the nephrons and down the renal tubules of the kidney.
From the kidneys, urine travels down two thin tubes called
ureters to the bladder. The ureters are about 8 to 10 inches long. Muscles in the ureter
walls constantly tighten and relax to force urine downward away from the kidneys. If urine
is allowed to stand still, or back up, a kidney infection can develop. Small amounts of
urine are emptied into the bladder from the ureters about every 10 to 15 seconds.
The bladder is a hollow muscular organ shaped like a balloon.
It sits in your pelvis and is held in place by ligaments attached to other organs and the
pelvic bones. The bladder stores urine until you are ready to go to the bathroom to empty
it. It swells into a round shape when it is full and gets smaller when empty. If the
urinary system is healthy, the bladder can hold up to 16 ounces (2 cups) of urine
comfortably for 2 to 5 hours.
Circular muscles called sphincters help keep urine from
leaking. The sphincter muscles close tightly like a rubber band around the opening of the
bladder into the urethra, the tube that allows urine to pass outside the body. Nerves in
the bladder tell you when it is time to urinate (empty your bladder). As the bladder first
fills with urine, you may notice a feeling that you need to urinate. The sensation to
urinate becomes stronger as the bladder continues to fill and reaches its limit. At that
point, nerves from the bladder send a message to the brain that the bladder is full, and
your urge to empty your bladder intensifies.
When you urinate, the brain signals the bladder muscles to
tighten, squeezing urine out of the bladder. At the same time, the brain signals the
sphincter muscles to relax. As these muscles relax, urine exits the bladder through the
urethra. When all the signals occur in thecorrect order, normal urination occurs.
- What Causes Problems in the
Urinary System?
- Problems in the urinary system can be caused by aging,
illness, or injury. As you get older, changes in the kidneys' structure cause them to lose
some of their ability to remove wastes from the blood. Also, the muscles in your ureters,
bladder, and urethra tend to lose some of their strength. You may have more urinary
infections because the bladder muscles do not tighten enough to empty your bladder
completely. A decrease in strength of muscles of the sphincters and the pelvis can also
cause incontinence, the unwanted leakage of urine. Illness or injury can also prevent the
kidneys from filtering the blood completely or block the passage of urine.
- How Are Problems in the Urinary
System Detected?
-
- Urinalysis is a test that studies the content of urine for
abnormal substances such as protein or signs of infection. This test involves urinating
into a special container and leaving the sample to be studied.
-
- Urodynamic tests evaluate the
storage of urine in the bladder and the flow of urine from the bladder through the
urethra. Your doctor may want to do a urodynamic test if you are having symptoms that
suggest problems with the muscles or nerves of your lower urinary system and pelvis
(ureters, bladder, urethra, and sphincter muscles).
-
- Urodynamic tests measure the contraction of the bladder muscle
as it fills and empties. The test is done by inserting a small tube called a catheter
through your urethra into your bladder to fill it either with water or a gas. Another
small tube is inserted into your rectum to measure the pressure put on your bladder when
you strain or cough. Other bladder tests use x-ray dye instead of water so that x-ray
pictures can be taken when the bladder fills and empties to detect any abnormalities in
the shape and function of the bladder. These tests take about an hour.
- What Are Some Disorders of the
Urinary System?
- Disorders of the urinary system range in severity from
easy-to-treat to life-threatening.
Benign prostatic hyperplasia (BPH)
is a condition in men that affects the prostate gland, which is part of the male
reproductive system. The prostate is located at the bottom of the bladder and surrounds
the urethra. BPH is an enlargement of the prostate gland that can interfere with urinary
function in older men. It causes blockage by squeezing the urethra, which can make it
difficult to urinate. Men with BPH frequently have other bladder symptoms including an
increase in frequency of bladder emptying both during the day and at night. Most men over
age 60 have some BPH, but not all have problems with blockage. There are many different
treatment options for BPH.
Interstitial cystitis (IC) is a chronic bladder disorder also
known as painful bladder syndrome and frequency-urgency-dysuria syndrome. In this
disorder, the bladder wall can become inflamed and irritated. The inflammation can lead to
scarring and stiffening of the bladder, decreased bladder capacity, pinpoint bleeding,
and, in rare cases, ulcers in the bladder lining. The cause of IC is unknown at this time.
Kidney stones is the term commonly used to refer to stones, or calculi, in the
urinary system. Stones form in the kidneys and may be found anywhere
in the urinary system. They vary in size. Some stones cause great pain while others cause
very little. The aim of treatment is to remove the stones, prevent infection, and prevent
recurrence. Both nonsurgical and surgical treatments are used. Kidney stones affect men
more often than women.
Prostatitis is inflammation of the prostate gland that results in urinary frequency
and urgency, burning or painful urination (dysuria), and pain in the lower back and
genital area, among other symptoms. In some cases, prostatitis is
caused by bacterial infection and can be treated with antibiotics. But the more common
forms of prostatitis are not associated with any known infecting organism. Antibiotics are
often ineffective in treating the nonbacterial forms of prostatitis.
Proteinuria is the presence of abnormal amounts of
protein in the urine. Healthy kidneys take wastes out of the blood but leave in protein.
Protein in the urine does not cause a problem by itself. But it may be a sign that your
kidneys are not working properly.
Renal (kidney) failure results when the
kidneys are not able to regulate water and chemicals in the body or remove waste products
from your blood. Acute renal failure (ARF) is the sudden onset of kidney failure. This can
be caused by an accident that injures the kidneys, loss of a lot of blood, or some drugs
or poisons. ARF may lead to permanent loss of kidney function. But if the kidneys are not
seriously damaged, they may recover. Chronic renal failure (CRF) is the gradual reduction
of kidney function that may lead to permanent kidney failure, or end-stage renal disease
(ESRD). You may go several years without knowing you have CRF.
Urinary tract infections (UTIs) are caused by bacteria in the
urinary tract. Women get UTIs more often than men. UTIs are treated with antibiotics.
Drinking lots of fluids also helps by flushing out the bacteria.
The name of the UTI depends on its location in the urinary tract. An infection in the
bladder is called cystitis. If the infection is in one or both of the kidneys, the
infection is called pyelonephritis. This type of UTI can cause serious damage to the
kidneys if it is not adequately treated.
Urinary incontinence, loss of bladder control, is the involuntary passage of urine.
There are many causes and types of incontinence, and many
treatment options. Treatments range from simple exercises to surgery. Women are affected
by urinary incontinence more often than men.
Urinary retention, or bladder-emptying problems, is
a common urological problem with many possible causes. Normally, urination can be
initiated voluntarily and the bladder empties completely. Urinary retention is the
abnormal holding of urine in the bladder. Acute urinary retention is the sudden inability
to urinate, causing pain and discomfort. Causes can include an obstruction in the urinary
system, stress, or neurologic problems. Chronic urinary retention refers to the persistent
presence of urine left in the bladder after incomplete emptying. Common causes of chronic
urinary retention are bladder muscle failure, nerve damage, or obstructions in the urinary
tract. Treatment for urinary retention depends on the cause.
- Who Can Help Me With a Urinary Problem?
-
- Your primary doctor can help you with some urinary problems.
Your pediatrician may be able to treat some of your child's urinary problems. But some
problems may require the attention of a urologist, a doctor who specializes in treating
problems of the urinary system and the male reproductive system. A gynecologist is a
doctor who specializes in the female reproductive system and may be able to help with some
urinary problems. A urogynecologist is a gynecologist who specializes in the female
urinary system. A nephrologist specializes in treating diseases of the kidney.
- Points To Remember
-
- Your urinary system filters waste and extra fluid from your
blood.Problems in the urinary system include kidney failure, urinary tract infections,
kidney stones, prostate enlargement, and bladder control problems.Health professionals who
treat urinary problems include general practitioners (your primary doctor), pediatricians,
urologists, gynecologists, urogynecologists, and nephrologists.
- Resources for More Information
American Foundation for Urologic Disease
1128 N. Charles Street
Baltimore, MD 21201
(800) 242-2383 or (410) 468-1800
admin@afud.org
-
American Kidney Fund
6110 Executive Boulevard
Suite 100
Rockville, MD 20852
(800) 638-8299 or (301) 881-3052
helpline@akfinc.org
American Society of Pediatric Nephrology
Department of Pediatrics
University of Wisconsin Children's Hospital
600 Highland Avenue
Madison, WI 53792-4108
(608) 265-6020
American Uro-Gynecologic Society
401 North Michigan Avenue
Chicago, IL 60611-4267
(312) 644-6610 ext. 4712
Interstitial Cystitis Association
P.O. Box 1553
Madison Square Station
New York, NY 10159
(800) ICA-1626 or (212) 979-6057
http://www.ichelp.org
National Association for Continence (NAFC)
P.O. Box 8310
Spartanburg, SC 29305-8310
(864) 579-7900 or (800) BLADDER
http://www.nafc.org/
National Kidney Foundation
30 East 33rd Street
New York, NY 10016
(800) 622-9010
http://www.kidney.org/
The Prostatitis Foundation
Information Distribution Center
Parkway Business Center
2029 Ireland Grove Road
Bloomington, IL 61704
(309) 664-6222
Mcapstone@aol.com
http://www.prostate.org/
The Simon Foundation for Continence
P.O. Box 835
Wilmette, IL 60091
(800) 23-SIMON or
(847) 864-3913 (main office)
simoninfo@simonfoundation.org
http://www.simonfoundation.org/
National Kidney and Urologic Diseases Information
Clearinghouse
3 Information Way
Bethesda, MD 20892-3580
E-mail: nkudic@info.niddk.nih.gov
|
