coma


coma
coma1
/koh"meuh/, n., pl. comas.
a state of prolonged unconsciousness, including a lack of response to stimuli, from which it is impossible to rouse a person.
[1640-50; < Gk kôma deep sleep]
coma2
/koh"meuh/, n., pl. comae /-mee/.
1. Astron. the nebulous envelope around the nucleus of a comet.
2. Optics. a monochromatic aberration of a lens or other optical system in which the image from a point source cannot be brought into focus, the image of a point having the shape of a comet.
3. Bot.
a. a tuft of silky hairs at the end of a seed.
b. the leafy crown of a tree; cluster of leaves at the end of a stem.
c. a terminal cluster of bracts, as in the pineapple.
[1660-70; < L: hair < Gk kóme]

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Complete lack of consciousness, with loss of reaction to stimulus and of spontaneous nervous activity.

It is usually associated with cerebral injury of metabolic or physical origin. Simple concussions cause short losses of consciousness. Coma from lack of oxygen may last several weeks and is often fatal. Coma caused by stroke can be sudden, while that caused by metabolic abnormalities (as in diabetes mellitus) or cerebral tumours comes on gradually. Treatment depends on the cause.

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      state of unconsciousness, characterized by loss of reaction to external stimuli and absence of spontaneous nervous activity, usually associated with injury to the cerebrum. Coma may accompany a number of metabolic disorders or physical injuries to the brain from disease or trauma.

      Different patterns of coma depend on the origin of the injury. Concussions (concussion) may cause losses of consciousness of short duration; in contrast, lack of oxygen (anoxia) may result in a coma that lasts for several weeks and is often fatal. stroke, a rupture or blockage of vessels supplying blood to the brain, can cause sudden loss of consciousness in some patients, while comas caused by metabolic abnormalities or cerebral tumours (tumour) are characterized by a more gradual onset, with stages of lethargy and stupor before true coma. Metabolic comas are also more likely to have associated brain seizures and usually leave pupillary light reflexes intact, whereas comas with physical causes usually eradicate this reflex.

      Common causes of metabolic coma include diabetes (diabetes mellitus), excessive consumption of alcohol (alcohol consumption), and barbiturate poisoning. In diabetes, low insulin levels allow the buildup of ketones (ketone), breakdown products of fat tissue that destroy the osmotic balance in the brain, damaging brain cells. Ingestion of large quantities of alcohol over a short period can cause a coma that may be treated by gastric lavage (stomach pump) in its early stages; alcohol combined with barbiturates is a common cause of coma in suicide attempts. Large doses of barbiturates alone will also produce coma by suppressing cerebral blood flow, thus causing anoxia. Gastric lavage soon after the drug is ingested may remove a sufficient amount of the barbiturate to allow recovery. For most metabolic comas, the first step in treatment is to protect the brain cells and attempt to eliminate the cause of coma. Assisted ventilation is often necessary. In some psychiatric conditions, such as catatonic schizophrenia, a comalike state may also occur.

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Universalium. 2010.

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  • coma — coma …   Dictionnaire des rimes

  • COMA — Le coma est un état caractérisé par la perte de la conscience et par la perte plus ou moins complète des fonctions de relation: sensibilité et motricité. Cependant, certaines fonctions végétatives (qui entretiennent la nutrition) sont… …   Encyclopédie Universelle

  • Coma — puede tener los siguientes significados: en medicina, coma (del griego κῶμα o κωμα sopor) es un estado severo de pérdida de consciencia. la coma [,] (del griego κόμμα corte) es un signo de puntuación. en matemáticas, al separador decimal entre… …   Wikipedia Español

  • coma — m. neurol. Estado de sopor profundo debido a una alteración del sistema reticular activador ascendente. El paciente ha perdido la sensibilidad, la movilidad y se muestra inconsciente pero conserva las funciones vegetativas (respiración,… …   Diccionario médico

  • coma — |ô| s. f. 1. Cabeleira. 2. Cabelo comprido. 3. Crina do cavalo. 4. Juba do leão. 5. Penas compridas que adornam a cabeça de certas aves. = PENACHO 6. Plumas do capacete. = PENACHO 7. Copa (do arvoredo). 8.  [Astronomia] Cabeleira de cometa. 9. … …   Dicionário da Língua Portuguesa

  • COMA — olim libertatis insigne, apud Gallos praesertim: unde Regalis capillitii ius priscis Francis, adeo celebre, apud Hottomannum, Francogalliae, c. 9. Aimoinum, de Gestis Francorum, l. 3. c. 61. etc. Certe omnes Galliae Reges usque ad Pippinum Caroli …   Hofmann J. Lexicon universale

  • Coma I — es un grupo de galaxias disperso que recibe éste nombre por estar muchos de sus miembros en la constelación de Coma Berenices. Se halla a apenas 5 millones de parsecs de la galaxia elíptica M87, el miembro central del Cúmulo de Virgo, y parece… …   Wikipedia Español

  • Coma — Пётр Рогуцкий лидер группы COMA во время концерта в Мегаклу …   Википедия

  • coma — CÓMA, come, s.f. (fiz.) 1. Aberaţie a sistemelor optice care constă în apariţia unei imagini în formă de cometă. 2. Aberaţie a lentilelor electronice, caracterizată prin apariţia unei estompări spre periferia imaginii. – Din fr. coma. Trimis de… …   Dicționar Român

  • coma — sustantivo masculino 1. (no contable) Pérdida de conciencia prolongada en que permanecen algunos enfermos graves: El accidentado estuvo un mes en estado de coma. sustantivo femenino 1. Signo ortográfico de puntuación que indica una separación o… …   Diccionario Salamanca de la Lengua Española

  • Coma — Verbrauchermärkte GmbH Co KG Rechtsform GmbH Co KG Gründung 1977 Sitz Meppen Mitarbeiter ca. 1.400 Website …   Deutsch Wikipedia


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