hibernation

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hibernation

 [hi″ber-na´shun]
a dormant state in which certain animals pass the winter, marked by deep sleep and sharp reduction in body temperature and metabolism.
artificial hibernation a state of reduced metabolism, muscle relaxation, and a twilight sleep resembling narcosis, produced by controlled inhibition of the sympathetic nervous system and causing attenuation of the homeostatic reactions of the organism.

hi·ber·na·tion

(hī'bĕr-nā'shŭn),
A torpid condition in which certain animals pass the cold months. True hibernators, such as woodchucks, ground squirrels, dormice, and some others, have body temperatures reduced to near the freezing point, with a very slow heartbeat, low metabolism, and infrequent respirations. Partial hibernators, such as bears, skunks, and raccoons, have reduced physiologic activity during the cold months, but they are not comatose. Compare: estivation.
Synonym(s): winter sleep
[L. hibernus, relating to winter]
Cardiology Myocardial hibernation
Physiology Astate of winter dormancy and hypothermia seen in bears and other animals

hi·ber·na·tion

(hī'bĕr-nā'shŭn)
A torpid condition in which some animal species pass the cold months.
Compare: estivation
Synonym(s): winter sleep.
[L. hibernus, relating to winter]

hibernation

a state of dormancy entered into by many animals during the winter, particularly those in cooler latitudes. Some temperate and arctic mammals, reptiles and some amphibians hibernate and, in this state, the METABOLISM is slowed down and the body temperature falls. Hibernation is generally triggered by cold weather and whilst body temperatures in mammals normally are maintained at the usual level, they may fall much lower and near to freezing point (in e.g. hamster), or to that of the surroundings (in e.g. bat).

True hibernators tend to be mid-sized animals as these can have sufficient food reserves without too large a surface area for heat loss. Bears are not true hibernators as their body temperature does not drop and they are able to awake from their winter ‘sleep’ very quickly. In temperate situations, rises in temperature may cause some animals temporarily to come out of hibernation. Compare AESTIVATION (1).

References in periodicals archive ?
The chipmunks and ground squirrels use a different hibernation alarm clock than marmots do, Inouye reported this month to a joint meeting in Orlando, Fla., of the Ecological Society of America and the British Ecological Society.