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Urology is the field of medicine that focuses on the urinary tracts of males and females, and of the male reproductive system. It is "multidisciplinary" in that the discipline includes management of "medical"
(i.e.., non-surgical) problems such as urinary infections and "surgical" problems such as the correction of congenital abnormalities of the urinary / reproductive systems and the surgical management of cancers involving the urinary and (male) reproductive organs. It includes the urethra, kidneys, ureters, urinary bladder, the male reproductive organs including the foreskin, testes, epididymis, vas deferens, seminal vesicles, and prostate.
Urology is closely related to the medical fields of andrology and gynecology. In men, the urinary system overlaps with the reproductive system, and in women the urinary tract opens into the vulva. In both sexes, the urinary and reproductive systems are close together, and often both affected by disease or disorders of one or the other.
The urinary system is a system of organs, tubes, muscles, and nerves that work together to create, store, and carry, urine. The urinary system includes two kidneys, two ureters, the urinary 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, especially the amounts of fluid and food 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 (200 to 250 mm) 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 fluid ounces (500 ml) 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 the correct 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.
Prostatitis is any form of inflammation of the prostate gland. Because women do not have a prostate gland, it is a condition only found in men.
Prostatitis may account for up to 25 percent of all office visits by young and middle-age men for complaints involving the genital and urinary systems.
Inflammation of the prostate leads to pain, often during voiding but also in back and rectum. Frequent urination and increased urgency may suggest a cystitis (bladder infection). Ejaculation may be painful, as the prostate contracts during emission of semen.
Prostate cancer is the most common type of cancer in men in the United States. Of all the men who are diagnosed with cancer each year, more than one-fourth have prostate cancer.
Kidney stones are solid accretions (crystals) of dissolved minerals in urine found inside the kidneys or ureters. Also known as nephrolithiasis, urolithiasis or renal calculi. They vary in size from as small as a grain of sand to as large as a golf ball. Kidney stones typically leave the body in the urine stream; if they grow relatively large before passing (on the order of millimeters), obstruction of a ureter and distention with urine can cause severe pain most commonly felt in the flank, lower abdomen and groin.
Conventional wisdom has held that consumption of too much calcium can aggravate the development of kidney stones, since the most common type of stone is calcium oxalate. However, strong evidence has accumulated demonstrating that low-calcium diets are associated with higher stone risk and vice-versa for the typical stone former. The relatively dense calcium renders these stones radio-opaque and they can be detected by a traditional X-ray of the abdomen that includes Kidneys, Ureters and Bladder-KUB. Computed tomography, a specialized X-ray, is by far the most accurate diagnostic test for the detection of kidney stones. Other examples of kidney stones include struvite (magnesium, ammonium and phosphate), uric acid, calcium phosphate, or cystine (the amino acid found only in people suffering from cystinuria). The formation of struvite stones is associated with the presence of certain bacteria which can split urea into ammonia, most commonly Proteus mirabilis . There are many types of kidney stone, and a person may be susceptible to only some of them.
Bladder cancer refers to any of several types of malignant growths of the urinary bladder.
Papillary transitional cell carcinoma is a cancer of the transitional epithelial cells of the bladder.
The greatest risk factor for bladder cancer is a genetic predisposition; it is also associated with smoking and occupational exposure to aniline-based dyes (such as in textile factories), as well as with petrol and other chemicals.
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