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Let's look at the urinary tract
The creation of urine begins in microscopic filters (glomeruli) in the two kidneys. These filters remove waste products from the blood. Thousands of these glomeruli make up each kidney.
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The urinary tract in men and women |
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The waste products leave each glomerulus through microscopic tubes. These tubes join larger tubes to form collecting systems that empty into still larger tubes, finally reaching a tube about the size of a drinking straw, called a ureter. The ureter from each kidney drains into the bladder, where the urine is stored. When the bladder is full, the person has an urge to urinate. With urination, the bladder contracts and forces the urine out into the urethra and then to the outside.
Men and women have two kidneys, two ureters, one bladder, and one urethra. In women, the urethra is a fairly straight tube leading from the bladder to the outside and is much shorter than in men. Because it is so straight and short in women, the urethra can be a path for bacteria to enter the bladder.
In men, the urethra is much longer and more crooked, and it does double duty as part of the reproductive system. Because of its dual role in men, the urethra is connected to parts of the male reproductive system—the prostate gland, the seminal vesicles, and the testis.
Where is the infection?
Normally, the urine does not contain any bacteria or infectious organisms (that is, it is sterile) when it is formed in the kidney. The urine stays sterile until it leaves the body, but it may pick up bacteria from the skin of the genital region as it leaves the body.
Most urinary tract infections are caused by bacteria that have invaded the urinary tract and started multiplying there. Less often, viruses, fungi, or yeast enter the urine.
In other words…
In women, the most common place for a urinary tract infection is the bladder. The medical term for a bladder infection is cystitis. (Cyst comes from the Greek word, kystis, meaning a sac or bladder; the ending -itis attached to a word means inflammation.)
Infection of the urethra is called urethritis. Infection of the kidneys is called pyelonephritis. (Pyelo comes from the Greek word, pyelos, which refers to the part of the kidney where the collecting system joins to form the ureter; nephros is the Greek word for kidney.) Your health care professional may call cystitis and urethritis a lower urinary tract infection and pyelonephritis an upper urinary tract infection.
Because of the longer urethra, which makes it harder for bacteria to enter the male urinary tract, men don't get bladder infections as often as women do. But men can get infection of the prostate (prostatitis). An infection in a man can also spread to the epididymis, where the sperm are stored. Such an infection is called epididymitis.
Like women, men can get kidney infections. Urethritis in a man is a little different from most urinary tract infections, because urethritis in men is usually a sexually transmitted disease, like gonorrhea. Men may talk about a "discharge," "a strain," or "a dose," when they have sexually transmitted urethritis.
A lower urinary tract infection in a woman whose physical makeup (anatomy) is normal is called an uncomplicated urinary tract infection. The urinary tract infection is called a complicated urinary tract infection if it occurs in a man. A urinary tract infection is also considered to be complicated if it occurs in a person whose urinary tract anatomy is abnormal, who has a nerve (neurologic) disease that interferes with urinating, whose urinary tract contains stones (for instance, in the bladder or kidney), or who has diabetes or sickle cell disease.
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