(2) Blood vessels contract. When the body is loosing too much heat, the
hypothalamus causes the blood vessels near the surface of the skin to contract
(become smaller). The blood vessels' decrease in size causes the vessels to loose
heat slower than normal. The contraction of the blood vessels causes the skin to look
WHAT CAUSES ABNORMAL TEMPERATURES?
When a person's body temperature is not within the normal temperature range,
the cause is usually an infection or a dangerous environmental condition.
a. Infection. An infection occurs when the body is invaded by harmful
microorganisms. When an infection occurs, the body attempts to destroy the invading
microorganisms. One method used by the body is raising the body's temperature to a
point where the invading microorganisms will be weakened or destroyed. When a
person has a body temperature above his normal body temperature, he is said to have
a fever. Another name for fever is pyrexia. Pyrexia comes from the Greek word "pyr,"
which means "on fire."
b. Environmental Conditions. Even though the body can maintain a normal
body temperature under most weather conditions, very hot or very cold conditions can
cause the hypothalamus to work improperly.
(1) Heatstroke. Sometimes the body cannot get rid of body heat fast
enough and the body temperature rises. This condition is most likely to happen when a
person is performing hard work in a hot climate. The rising body temperature is too
much for the hypothalamus to handle and it begins to lose control of the body's cooling
mechanisms. When the body stops perspiring, the body temperature continues to rise.
This condition is known as heatstroke. The person will usually lose consciousness.
Rapid cooling of the body is essential in the preventing major organ damage and death
in the heatstroke patient.
(2) Generalized hypothermia. Generalized hypothermia refers to the
lowering of the body temperature below normal levels. Death will result if the body
temperature is not restored. For example, suppose a person falls off a ship into cold
ocean water. The body looses heat to the cold water faster than the body can produce
heat. If the person is removed from the cold conditions (pulled out of the water onto a
boat, for example), the body may not be able to warm itself. In such a case, an outside
source of heat (such as another person lying body to body with the victim) is needed to
restore normal body temperature to the victim until the hypothalamus is functioning
properly again. The body must be warmed slowly and in a controlled environment to
prevent overwhelming of the body's system.