Uriburu \ l ii-re- , bu-rU\ / Jose Felix (b. July 20, 1868, Salta, Arg.—d. April 29, 1932, Paris, Fr.) Argentine soldier and dictator. Nephew of a former president, he was a firm believer in class privileges. A visit to Ger¬ many made him an ardent admirer of Prussian militarism. In 1930 he led a coup against Hipolito Irigoyen’s liberal regime, replacing the governing class with an elite representing the landed oligarchy, dissolving the leg¬ islature, and revising the laws to prohibit liberal-radicals from political participation. In 1931 he arranged a fraudulent election to ensure the oli¬ garchy’s continued control and stepped down in favour of a fellow officer, Agustrn Justo.
uric acid Vyur-ik\ Heterocyclic compound of the purine type, the end product of metabolism of the purines in nucleic acids in many animals, including humans. It is excreted by reptiles and birds as the chief nitrog¬ enous end product of protein breakdown. Small quantities are normally found in human blood; in gout, levels are abnormally high. Uric acid is used industrially in organic synthesis.
urinalysis \ l yur-3- , na-lo-s9s\ Laboratory examination of a urine sample for clinical information. Abnormal concentrations of substances normally found in urine or presence of those that are not may indicate a disorder. Colour, specific gravity, or volume changes may reveal a specific disease or injury. Significant findings include high glucose and acetone in diabe¬ tes mellitus; various nitrogen compounds, pigments, amino acids, and their metabolic products in disorders of the enzymes that act on them; uric acid in gout; and urea, albumins, and globulins in kidney disease. Hormones may be evidence of pregnancy or endocrine imbalance. Urinalysis can also detect poisons and drugs.
urinary system or renal \'re-nol\ system System that produces and discharges urine to rid the body of waste products. It consists of the kid¬ neys, which balance electrolytes in blood, retaining and adding needed ones and removing unneeded or dangerous ones for excretion; the ureters, two thin muscular tubes 10-12 in. (25-30 cm) long that move the urine by peristalsis; the hollow, muscular bladder, which receives and stores it; and the urethra, through which it leaves the body. In women the urethra is 1.5 in. (4 cm) long. In men it is longer (since it passes through the penis), about 8 in. (20 cm), and carries semen from the prostate gland as well as urine. Urinary disorders, which can lead to dehydration or edema and to a dangerous buildup of waste and toxic substances, include kidney failure, tumours, and bladder and kidney stones.
urination Process of excreting urine from the bladder (see urinary sys¬ tem). Nerve centres in the spinal cord, brain stem, and cerebral cortex control it through involuntary and voluntary muscles. The need to void is felt when the bladder holds 3.5-5 oz (100-150 ml) of urine and becomes uncomfortable at a volume of 14-15 oz (350^-00 ml). The detrusor con¬ tracts and the sphincter (muscular constriction) of the urethra relaxes to
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1976 I urine ► Uruguay
empty the bladder. Normally it empties completely, but bladder stones or prostatic disorders can block outflow; poor muscle tone (especially in older women) or certain nervous system disorders can cause loss of control of urination (incontinence).
urine Liquid solution of metabolic wastes and other, often toxic, sub¬ stances filtered from plasma. The fluid in the Bowman capsule at the start of each nephron is essentially plasma without the large molecules (e.g., proteins). The concentrated fluid (final urine) that exits the kidney consists of water, urea, inorganic salts, uric acid, creatinine, ammonia, and broken- down blood pigments, including urochrome, which makes urine yellow, plus any unusual substances not reabsorbed into the blood. This is then excreted. See also hematuria; urinalysis; urinary system; urination.
URL in full Uniform Resource Locator Address of a resource on the Internet. The resource can be any type of file stored on a server, such as a Web page, a text file, a graphics file, or an application program. The address contains three elements: the type of protocol used to access the file (e.g., HTTP for a Web page, ftp for an FTP site); the domain name or IP address of the server where the file resides; and, optionally, the pathname to the file (i.e., description of the file’s location). For example, the URL http://www.britannica.com/heritage instructs the browser to use the HTTP protocol, go to the www.britannica.com Web server, and access the file named heritage.
Urmia, Lake Persian Daryacheh-ye Orumiyyeh
X.dar-ya-'che-ye-u-.ru-'me-yoV Shallow, saline lake, northwestern Iran. The largest lake in the Middle East, it covers an area that varies from 2,000 to 2,300 sq mi (5,200 to 6,000 sq km). It is about 87 mi (140 km) long and 25-35 mi (40-55 km) wide, with a maximum depth of 53 ft (16 m). There is a cluster of about 50 tiny islands at its southern part. Fed by three rivers, it has no outlet. It has been protected since 1967.
Urnfield culture Late Bronze Age culture of Europe, so called because its people placed their cremated dead in urns. This culture spread from east-central Europe and northern Italy in the 12th century bc and later to Ukraine, Sicily, Scandinavia, France, and Spain. In some areas barrows marked the graves. The culture was warlike, with fortified settlements and bronze weapons, including the slashing sword. The uniformity of the cul¬ ture and the persistence of certain pottery and metal forms apparently had great influence on Early Iron Age culture.
urogenital malformation Defect in the organs or tissues of the uri¬ nary system or in the sex organs (genitals). In polycystic kidney disease (an inherited disease), cysts of varying size enlarge one or both kidneys. Kidneys may have abnormal shapes or may be fused. In megaloureter, the ureter’s diameter is enlarged. Males may have epispadias or hypospadias, in which the urethra opens on the upper surface or the underside, respec¬ tively, of the penis, or cryptorchidism (undescended testicles), in which one or both testes have not descended from the abdomen into the scro¬ tum before birth. Female genital system malformations include agenesis of the ovaries, vagina, or uterus and abnormally shaped uterus.
urology \yu-'ra-l9-je\ Medical specialty dealing with the urinary system and male reproductive organs. It traces its origin to medieval lithologists, itinerant healers who specialized in surgical removal of bladder stones. The Spanish surgeon Francisco Diaz wrote the first treatises on urinary- tract disease (1588) and is regarded as the founder of modem urology. Most modem urological procedures originated in the 19th century. Today, urologists use bladder catheters (see catheterization), the cystoscope (to view the inside of the bladder), and various diagnostic imaging techniques; treat prostatic disorders; perform vasectomies; and may surgically remove stones in the urinary tract and cancers of the kidneys, bladder, and tes¬ ticles. Urology deals mostly with male patients; the urinary tract in females may be treated by gynecologists (see obstetrics and gynecology).
Urquiza Vur-'ke-saV, Justo Jose de (b. Oct. 18,1801, Arroyo Urquiza, Viceroyalty of the Rio de la Plata—d. April 11, 1870, Entre Rios province, Arg.) Argentinian soldier and statesman who helped overthrow Juan Man¬ uel de Rosas. He became governor of Entre Rios province in 1841 and allied himself with other provincial leaders to overthrow the dictatorial Rosas in 1852. As provisional dictator, he called a constitutional convention that sanctioned a constitution modeled on that of the U.S. All provinces accepted it, but the province of Buenos Aires, determined to lead the nation, refused to join the new union until 1859. Urquiza stepped down in 1860 and led the Argentinian army in the Paraguayan War. He and his sons were assassinated by a political rival. See also Bartolome Mitre.