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clear, amber-colored fluid formed by the kidneys that carries metabolic wastes out of the body (see urinary systemurinary system,
group of organs of the body concerned with excretion of urine, that is, water and the waste products of metabolism. In humans, the kidneys are two small organs situated near the vertebral column at the small of the back, the left lying somewhat higher than the
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). As the blood circulates it collects excretory products from the tissues and these substances are separated from the blood by the kidneys and eliminated chiefly in the urine. The urine is then stored in the bladderbladder, urinary,
muscular sac located in the pelvis that stores urine and contracts to expel it from the body. Urine enters the bladder from the kidneys through the ureters and is discharged from the body via the urethra. The bladder of the adult human can hold over a pint (0.
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 and passes out of the body via the urethraurethra
, canal in most mammals that carries urine from the bladder to the outside of the body; in the male it also serves as a genital duct. The urethra is about 1 1-2 in. long (3.8 cm) in women, terminating above the vaginal opening. In men the urethra is about 8 in.
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. The amount passed depends on fluid intake and other factors. Urine is 95% water, in which are dissolved urea, uric acid, creatinine, and other waste products. Normal urine also contains small amounts of substances ordinarily utilized by the body, such as sodium, potassium, and calcium; these substances are excreted by the kidneys when excessive amounts are present in the bloodstream. Analysis of the urine is important in detecting diseases of the urogenital organs, as well as disorders of other body systems.
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An aqueous solution of organic and inorganic substances, mostly waste products of metabolism. The kidneys maintain the internal milieu of the body by excreting these waste products and adjusting the loss of water and electrolytes to keep the body fluids relatively constant in amount and composition. The urine normally is clear and has a specific gravity of 1.017–1.020, depending upon the amount of fluid ingested, perspiration, and diet. The increase in specific gravity above that of water is due to the presence of dissolved solids, about 60% of which are organic substances such as urea, uric acid, creatinine, and ammonia; and 40% of which are inorganic substances such as sodium, chloride, calcium, potassium, phosphates, and sulfates. Its reaction is usually acid (pH 6) but this too varies with the diet. It usually has a faint yellow color due to a urochrome pigment, but the color varies depending upon the degree of concentration, and the ingestion of certain foods (for example, rhubarb) or cathartics. It usually has a characteristic aromatic odor, the cause of which is not known. See Kidney, Urea, Uric acid, Urinary system

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a human and animal excretion that is produced by the kidneys. Water, salts, end products of metabolism, and foreign substances are excreted with the urine. Human urine is normally a transparent, yellow fluid; the color is dependent on the presence of several pigments, chiefly the products of the decomposition of hemoglobin. The specific gravity of urine is 1.010–1.025 g/cm3, and the pH ranges from 4.8 to 8.0. Intake of protein-rich foods results in acidic urine, while consumption of vegetables causes the urine to be weakly alkaline. About 96 percent of urine consists of water; 1.5 percent, of salts; and 2.5 percent, of such organic metabolic products as urea and uric acid. Urine and blood plasma contain the same salts—mainly NaCl, and also sulfates, phosphates, and carbonates of potassium, magnesium, and ammonium.

An adult excretes 1,200–1,600 ml of urine daily. The volume and composition of the urine are dependent on several factors, including the nature of an individual’s liquid intake, the type of food eaten, the temperature of the external environment, and stress factors. Urinalysis is a diagnostic method that reflects the condition of the kidneys, of the metabolism in other organs and tissues, and of the body as a whole.


Gulevich, V. S. Analiz mochi. Leningrad, 1945.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


The fluid excreted by the kidneys.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


the pale yellow slightly acid fluid excreted by the kidneys, containing waste products removed from the blood. It is stored in the urinary bladder and discharged through the urethra
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
A midstream urine test was still EBOV PCR-positive ([C.sub.t] value 39.6); PCR of her sweat swab sample was inhibited (online Technical Appendix).
Their early morning midstream urine sample was collected in open mouth sterilized plastic containers and cultured within 4 h.
(3) This is confirmed in the presence of significant bacteriuria based on isolation of [greater than or equal to] [10.sup.5] cfu/ml of same species of bacteria in properly collected and transported midstream urine during a screening test.
"At the first sign of infection, the patient is instructed to obtain a midstream urine sample ...
Midstream urine specimens are recommended for microbiological culture and antimicrobial-susceptibility resting because of reduced cellular and microbial contamination compared to initial urine specimens.
The simplest method is to put an adhesive bag on the child or to try to catch midstream urine in a container, such as the catch technique.
These included clean catch midstream urine, catheter, suprapubic and nephrostomy samples.
Using bladder cultures as a gold standard, midstream urine culture had a specificity and sensitivity of >97% at a threshold of 1000 CFU/mL.
The other 25 patients were instructed to collect a clean-catch midstream urine sample in a sterile container.
YOUR doctor will want to check a midstream urine sample for infection.