The liquid the KIDNEYS generate to pass wastes and excess fluid from the body. The typical adult makes and passes between 1,500 and 3,000 milliliters (1.5 to 3 liters) of urine every 24 hours. Numerous variables influence the volume and composition or urine, though in general urine is 95 percent water and 5 percent suspended or dissolved solids.
Most of the solids urine contains are organic wastes in the forms of urea, uric acid, creatinine, and ammonia. These are the nitrogen-based waste byproducts of METABOLISM that the kidneys filter from the BLOOD. The urine also contains minerals (electrolytes) the kidneys excrete to maintain the body’s electrolyte and fluid balance. Excreted electrolytes include sodium, potassium, chloride, magnesium, phosphate, and calcium. Normal urine may contain small amounts of ALBUMIN (protein).
Urine of normal concentration is pale yellow and has no odor. Dilute urine is colorless; concentrated urine can appear dark yellow to orange. Dietary substances, certain medications, and certain health conditions can alter the color as well as the odor of the urine. Normal urine is slightly acidic and has a specific gravity of 1.010 to 1.025, slightly above that of water. Deviations from normal urine composition and concentration suggest various health conditions and may require diagnostic evaluation.
For further discussion of the urine within the context of the urinary system’s structure and function please see the overview section “The Urinary System.”
See also ALBUMINURIA; ANURIA; CYSTINURIA; HEMATURIA; OLIGURIA; UREMIA; UROLITHIASIS.
Resource: Facts On File Encyclopedia Of Health And Medicine
At birth the structures of the urinary system are fully developed and function under the automatic control of the NERVOUS SYSTEM. The newborn’s KIDNEYS filter BLOOD and make URINE. The BLADDER collects the urine and, when it fills to a point that triggers the micturition REFLEX, it empties to drain urine via the URETHRA to outside the body. Voluntary
Excessive excretion of ALBUMIN, a form of protein, into the URINE. Albuminuria, also called proteinuria, typically indicates kidney conditions that affect the glomeruli (the tubular structures within the KIDNEYS that filter wastes and excess water from the BLOOD to excrete in the urine). Such conditions include GLOMERULONEPHRITIS, GLOMERULOSCLEROSIS,
What is Alport’s Syndrome An inherited genetic disorder in which one, two, or three mutations occur in the GENE that encodes type IV collagen formations, also called basement membranes. The mutations affect up to three of the six protein chains (alpha-3, alpha-4, and alpha-5) that make up type IV collagen, which is a foundation for a number of
What is Anuria and Definition Anuria - The failure to produce URINE. Numerous circumstances can result in anuria, from severe DEHYDRATION and severe HYPOTENSION (low BLOOD PRESSURE) to END-STAGE RENAL DISEASE (ESRD) and RENAL FAILURE. Anuria requires prompt medical evaluation to determine and remedy the underlying cause. Without such correction, waste
What is Bladder and Definition A muscular, saclike structure in the lower pelvis that serves as a reservoir for the URINE the KIDNEYS produce. In women the bladder is in front of and slightly below the UTERUS. During PREGNANCY the expanding uterus limits the bladder’s ability to expand, accounting for the URINARY FREQUENCY common in pregnancy’s
What is Uremia and Definition Uremia is a serious condition in which nitrogenbased toxins such as urea and creatinine, the primary waste products of METABOLISM, accumulate in the BLOOD because the KIDNEYS are unable to filter them out and pass them from the body via the URINE. Uremia indicates RENAL FAILURE. Urologists sometimes use the term azotemia to
Ureter, in a human organism, is a muscular tube, fairly thick and rigid, that leads URINE from the kidney to the urinary BLADDER. Both of the two tubular structures arise from the renal pelvis and collect the urine from the kidney’s collecting tubules. Both ureters with the inner diameter of 3 or 4 millimeters exit the kidney at the hilus. Then, the
A narrow, somewhat muscular tube that carries URINE from the BLADDER to the outside of the body. The point of exit is the urinary or urethral meatus. The urethral sphincter MUSCLE at the base of the bladder controls the release of urine into the urethra. Once the urethral sphincter relaxes to let urine pass, the urine flows to the outside of the body until
What is Urethral Stricture Narrowing of the URETHRA, impeding the passage of URINE from the BLADDER to the outside of the body. Urethral stricture may be congenital (present at birth) or acquired such as through scarring resulting from repeated URETHRITIS, BLADDER CATHETERIZATION, and other irritations to the urethra. BENIGN PROSTATIC HYPERPLASIA (BPH) and
What is Urethritis and Definition INFLAMMATION of an URETER. INFECTION, typically a sexually transmitted disease (STD), is the most common cause of urethritis though urethritis may occur as a result of inflammation or irritation from trauma such as occurs with BLADDER CATHETERIZATION or CYSTOSCOPY. Traumatic urethritis improves rapidly when the source of