Definition and causes of hibernation

Positron emission tomography depicts metabolic viability in myocardium with persistent hour thallium defects observed with single photon emission CT. Assess the presence of available target vessels for bypass or angioplasty.

Morphological studies in acute experimental ischemia and intraoperatory myocardial biopsies.

How Hibernation Works

For example, only two species of reptiles are found north of the Arctic Circlebut great numbers of birds live and breed there. The benefits of warm-bloodedness require the expenditure of large amounts of energy through the year and make a heavy demand on available food supplies.

The results of the Coronary Artery Surgery Study CASSin which bypass surgery was compared with medical treatment, indicate that patients with multivessel disease and poor ventricular function benefited most from surgery in terms of survival. Role of technetiumm Tcm-MIBI is only minimally redistributed, and it is not taken up by necrotic myocardium.

The typical winter season for obligate hibernators is characterized by periods of torpor interrupted by periodic, euthermic arousals, during which body temperatures and heart rates are restored to more typical levels.

How Hibernation Works

The chipmunk Eutamias is an example of what has been termed a shallow hibernator, as are bears and raccoons. Endocrine activity The male sex hormone testosterone stimulates reproductive activity.

A similar state, known as estivation, occurs in some desert animals during the dry months of summer. At dusk, the rate drops first to a sleeping level and then plunges to a torpid level of about 0.

Hibernating and Stunned Myocardium Imaging

Unlike poikilotherms, however, hibernators still retain a measure of temperature control and can change their metabolic levels as required. One group is exemplified by the golden hamster ; it waits a variable time of from one to three months in the cold and then enters hibernation in one major temperature reduction.

The disease has occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or MRA scans. In the woodchuck, the rate may drop from to 68 heartbeats per minute within 30 minutes. The importance of understanding hibernation Scientists are interested in discovering the mechanisms that control hibernation and arousal, and the means by which animals survive such critically low metabolic activity.

In clinical practice, several strategies are used for patients with severe LV dysfunction. Just before daybreak, the bird awakens for another activity period. See the image below.

Changes in the circulatory system involving constriction narrowing of posterior vessels and the favouring of anterior circulation allow the brain temperature of hibernators to remain a few degrees warmer than the environmental level.

Only three orders of placental mammals display such behaviour: It drops its body temperature up to 60 degrees Fahrenheit and can live up to days on 10 grams of stored body fat.


If you can't get out of hibernate, you most likely have a serious problem. Depre C, Vatner SF.Jun 29,  · Certainly, chronic resting ischemia causes hibernation.


In patients with severe CAD, therefore, the limited flow reserve leads to development of myocardial ischemia, even with a small increase in the oxygen demand, such as in ordinary daily activities and exercise. Hibernation allows animals to survive in harsh climates where others would perish.

This lesson defines hibernation, discusses which animals. medical Definition of hibernate hibernated ; hibernating: to pass the winter in a torpid or resting state; especially: to pass the winter in a torpid condition in which the body temperature drops to a little above freezing and metabolic activity is reduced nearly to zero — compare estivate.

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.

Hibernation: Definition Hibernation is an inactive, sleep like state that animals must go and at least one bird enter during the winter.


Animals that hibernate shelter. Hibernate means that a animal stocks up on food and then sleeps throughout winter. Hibernation occurs in mammals like bears and squirrels during the winter, where they store food in the fall, and then sleep throughout the entire winter season, and wake up in the spring.

Definition and causes of hibernation
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