Hibernating animals stay at a low body temperature throughout the winter so that they will not need to use so many body resources. If they maintained a high body temperature during this time, they would need to expend many calories to do so. During the winter, food is much less available for these animals and they would likely be unable to find enough food to maintain that body heat. They would starve.
Induced hypothermia is used mainly on people who have suffered cardiac arrest or spinal cord injury. The reasons for the effect are not completely clear, but inducing hypothermia does help prevent such patients from suffering strokes.
Hibernation is a behavior displayed by some animals living in very cold regions whereby during winter they enter in to a state of inactive sleep like existence for extended periods. This kind of hibernation is accompanied by appreciable drop in heart beat rate and body temperature of these animals. This practice enables them to conserve their energy during the very cold winter when the energy required to keep the body at its normal temperature is very high. Usually in very severe winters these animals also find it difficult to hunt for and find food. The practice of hibernation enables them to live for extended periods without food, using their body fat for their energy requirements.
Considering how an animal as big as bear can hibernate, Japanese researchers have discovered that there is a hormone responsible for this state of sleep in which some animals get, along with the coming of cold season. Scientists have studied hibernation in squirrels, and found that before hibernation occurs a drop of concentration of a certain protein, called HP (hibernation specific protein) from blood, which then lasts for the whole duration of hibernation.When HP blood levels begin to increase ,hibernation ends.
The scientists noticed that the HP's in the blood is inversely proportional to its level in the brain. While the level of HP in blood drops, hormone concentration in spinal fluid grows very quickly. The importance of protein was confirmed by the fact that when animals received treatment with anti-body that blocked HP activity in the brain, the period of hibernation was reduced dramatically.
Higher temperature means higher internal energy and lower temperature means lower internal energy.
Therapeutic hypothermia is a new and effective neuroprotective method in patients, after cardiac arrest. It is assumed that it would inhibit many of the chemical reactions associated with reperfusion injuries. These reactions include production of oxygen free radicals, release of exciting amino-acids and disorders of calcium metabolism, which, in turn, can cause mitochondrial damages and cell death.
Animals that hibernate include bats, some species of ground squirrels and other rodents, mouse lemurs, the European Hedgehog and other insectivores, monotremes and marsupials. Hibernation is a state of inactivity and metabolic depression in animals, characterized by lower body temperature, slower breathing, and lower metabolic rate. Hibernating animals conserve food, especially during winter when food is short, tapping energy reserves, body fat, at a slow rate.
A mild drop in body temperature is common during surgery. Hypothermia is a condition in which an organism's temperature drops below that required for normal metabolism and body functions. Hypothermia is defined as any body temperature below 35.0 °C (95.0 °F). Hypothermia is the opposite of hyperthermia which is present in heat exhaustion and heat stroke.