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Hypothermia
Science Background
BIOLOGY
Human
Physiology
Body temperature regulation
Warm-blooded animals (such as humans) body temperature regulation is important. Your
body reacts automatically on body temperature changes. A constant body temperature is
important, as all body processes are temperature dependent.
The concept body temperature is often confused with the core temperature, the
temperature of the internal body. The skin temperature is used for the exterior (the skin,
libs and subcutaneous fat).
Your body checks continuous with heat receptors in the skin and in the core. These
receptors are located in the skin and hypothalamus. In the hypothalamus, all the
information of the receptors is processed and compared with the desired temperature.
When needed, thermoregulation will take place from the hypothalamus to adjust the core
temperature. The blood flow in the skin can be adjusted; by narrowing less blood flows
through the vessels and less heat will be released. Sweating causes evaporation, a
process, which take heat energy from the body. Finally, all body processes create heat.
Cold chills are fast muscle contractions to ensure an increase in body temperature.
Hypothermia
Hypothermia occurs when the body releases more heat than it produces. This may be
caused by cold air/water temperature or by abnormalities in metabolism. Hypothermia is a
gradual process involving three stages:
1. Mild hypothermia; in this phase the core temperature is between 33-35 °C. The
person is cold, heart rate and breathing are accelerated and peripheral blood
vessels constrict.
2. Moderate hypothermia; in this phase, the core temperature is between 30-33 ° C.
The metabolism has slowed down causing stiffness and muscle strength decreases
substantially. In addition, decrease in the consciousness takes place.
3. Severe hypothermia; in this phase, the core temperature is below 30 ° C. The
hypothermic person is unconscious, breathing is absent and heart rate is weak.
Surface-area-to-volume ratio
In warm-blooded animals, the relationship between surface area and volume is important.
A smaller body has a relative greater body surface. The larger the surface area in relation
to the volume, the more energy an animal needs in order to regulate its body temperature.
After all heat losses through the surface is significant. The surface-volume ratio also plays
an important role in water loss due to evaporation.
Hypothermia – Science Background
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