| vasovagal | Relating to the action of the vagus nerve upon the blood vessels. (05 Mar 2000) |
|---|---|
| vasovagal attack | <syndrome> Syndrome consisting of palpitation, chest pain, respiratory difficulties, and disturbances in gastric motility; once attributed to vagal stimulation, now considered psychogenic (anxiety neurosis). Synonym: vagal attack, vasovagal attack. (05 Mar 2000) |
| vasovagal epilepsy | Episodes of autonomic dysfunction presumably due to diencephalic irritation. Synonym: diencephalic epilepsy, vasomotor epilepsy, vasovagal epilepsy. (05 Mar 2000) |
| vasovagal syncope | A form of syncope (fainting) that occurs as a part of a normal physiologic response to stress (often emotional stress). The individual becomes lightheaded, nauseated, flushed, feels warm and then may lose consciousness for several seconds. (27 Sep 1997) |
| vasovagal syndrome | gowers' syndrome |
| syncope, vasovagal | A transient vascular and neurogenic reaction marked by pallor, nausea, sweating, bradycardia, and rapid fall in arterial blood pressure which, when below a critical level, results in loss of consciousness and characteristic electroencephalographic changes. It is most often evoked by emotional stress associated with fear or pain. It is also called vasovagal attack and gowers' syndrome. (12 Dec 1998) |
| accelerated reaction | A response occurring in a shorter time than expected; the cutaneous manifestations occurring during the period between the second and tenth day following smallpox vaccination; because it is intermediate between a primary reaction and an immediate reaction, it is regarded as evidence of some degree of resistance. Synonym: vaccinoid reaction. (05 Mar 2000) |
| acid reaction | Any test by which an acid reaction is recognised such as the change of blue litmus paper to red, an excess of hydrogen ions over hydroxide ions in aqueous solution indicated by a pH value less than 7 (at 22캜). Compare: dissociation constant of water. (05 Mar 2000) |
| acute-phase reaction | <immunology, rheumatology> Refers to the changes in synthesis of certain proteins within the serum during an inflammatory response, which provides rapid protection for the host against microorganisms via non-specific defense mechanisms. It consists of fever, an increase in inflammatory humoral factors, and an increased synthesis by hepatocytes of a number of proteins or glycoproteins usually found in the plasma; the reaction is mediated by endogenous pyrogens, the hypothalamus, adrenal hormones, and other factors. (12 Jul 2000) |
| acute situational reaction | An acute emotional reaction related to extreme environmental stress. Synonym: acute situational reaction. (05 Mar 2000) |
| acute stress reaction | A sudden bout of anxiety that is often accompanied by the features of hyperventilation (tingling around mouth and in fingertips, rapid breathing, faintness or fainting). (27 Sep 1997) |
| addition reaction | <chemistry> Any reaction in which two chemicals combine to form a single chemical. (15 Jan 1998) |
| adverse drug reaction reporting systems | Systems developed for collecting reports from government agencies, manufacturers, hospitals, physicians, and other sources on adverse drug reactions. (12 Dec 1998) |
| adverse reaction | Any undesirable or unwanted consequence of a preventive, diagnostic, or therapeutic procedure or regimen. (05 Mar 2000) |
| agar-gel reaction | <immunology> The reaction between an antibody and an antigen during an immunology lab procedure where the two are allowed to diffuse toward each other through an agar-gel medium. Lines of precipitation form in the places on the gel where the two react with each other and shows where the reaction has occurred. (09 Oct 1997) |