| osmolal clearance | The volume of urine that would be excreted per minute if the urinary solutes were accompanied by just enough water to make the urine isosmotic with plasma, i.e., so that the solute excretion did not change the osmolality of body fluids. To calculate it, the volume of urine excreted per minute is multiplied by the urinary osmolality (usually measured by freezing point depression) and divided by the plasma osmolality. Osmolal clearance is less than actual urine flow when urine is hyposmotic and exceeds it when urine is hyperosmotic. (05 Mar 2000) |
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| endogenous creatinine clearance | A term distinguishing measurements based on the creatinine normally present in plasma; since no infusion is necessary, an average value may be obtained by collecting urine for a long period, e.g., 24 hours. (05 Mar 2000) |
| exogenous creatinine clearance | A term distinguishing measurements based on infusing creatinine intravenously to raise its plasma concentration and facilitate its accurate chemical determination. (05 Mar 2000) |
| urea clearance | The volume of plasma (or blood) that would be completely cleared of urea by one minute's excretion of urine; originally calculated as urine flow multiplied by urine urea concentration divided by concentration of urea in whole blood rather than plasma, representing blood urea clearance rather than plasma urea clearance. (05 Mar 2000) |
| urea clearance test | A test of renal function based on urea clearance. (05 Mar 2000) |
| free water clearance | The amount of water excreted in the urine beyond that which would accompany the excreted solutes if the urine were isosmotic with plasma; it represents the loss of body water in excess of solute tending to raise body osmolality and making urine hyposmotic. Unlike other clearance's, it is calculated by subtracting the osmolal clearance from the actual volume of urine excreted per minute. A negative value for free water clearance represents the amount of water that the body has reclaimed from isosmotic tubule fluid to make the urine hyperosmotic and to lower body osmolality. (05 Mar 2000) |
| adenocarcinoma, bronchiolo-alveolar | A carcinoma thought to be derived from epithelium of terminal bronchioles, in which the neoplastic tissue extends along the alveolar walls and grows in small masses within the alveoli. Involvement may be uniformly diffuse and massive, or nodular, or lobular. The neoplastic cells are cuboidal or columnar and form papillary structures. Mucin may be demonstrated in some of the cells and in the material in the alveoli, which also includes denuded cells. Metastases in regional lymph nodes, and in even more distant sites, are known to occur, but are infrequent. (12 Dec 1998) |
| alveolar | <anatomy> Of, pertaining to, or resembling, alveoli or little cells, sacs, or sockets. Alveolar processes, the processes of the maxillary bones, containing the sockets of the teeth. Origin: L. Alveolus a small hollow or cavity: cf. F. Alveolaire. Source: Websters Dictionary (01 Mar 1998) |
| alveolar abscess | A pocket of pus adjacent to or within (apical abscess) the tooth's root caused by plaque and calculus invasion. Symptoms include tooth pain and tenderness that may be accompanied by facial swelling and a fever. Treatment includes antibiotics and a thorough cleansing of the infected site by a dentist. See: apical abscess. (27 Sep 1997) |
| alveolar adenocarcinoma | <tumour> Adenocarcinoma of the lung in which tumour cells form structures resembling alveoli. (05 Mar 2000) |
| alveolar air | The gas in the pulmonary alveoli, where O2-CO2 exchange with pulmonary capillary blood occurs. Synonym: alveolar air. (05 Mar 2000) |
| alveolar angle | The angle between the horizontal plane and a line connecting the base of the nasal spine and the middle point of the projection of the alveolus of the maxilla. (05 Mar 2000) |
| alveolar arch of mandible | The free margin of the alveolar process of the mandible. Synonym: arcus alveolaris mandibulae, limbus alveolaris. (05 Mar 2000) |
| alveolar arch of maxilla | The free border of the alveolar process of the maxilla. Synonym: arcus alveolaris maxillae, limbus alveolaris. (05 Mar 2000) |
| alveolar-arterial oxygen difference | The difference or gradient between the partial pressure of oxygen in the alveolar spaces and the arterial blood: P(A-a)02. Normally in young adults this value is less than 20 mm Hg. See: alveolar gas equation. (05 Mar 2000) |