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Hyperthermia and Hypothermia
Hyperthermia
An increase in core temperature without an accompanying reset of the hypothalamic set point is known as hyperthermia. There are different types of hyperthermia that can occur. Firstly, it’s exercise hyperthermia whereby the core temperature may approach 40°C without injury as long as heat loss mechanisms are effective. The other is Heat stroke whereby temperatures may reach beyond 40°C. High core temperatures may cause brain damage and death; symptoms include dizziness, nausea, absence of sweating, loss of consciousness. Furthermore, hot and humid weather can decrease effectiveness of cooling by evaporation contributing to heat stroke. Lastly, it is food – diet-induced thermogenesis. The basal metabolic rate of a person increases 10-15% after a meal due to synthesis of glycogen and fat for storage, leading to rise of temperatures.
Hypothermia
A decrease in core temperature without an accompanying reset of the hypothalamic set point is known as hypothermia. If the body temperatures drop below 35°C, metabolic and thermoregulatory processes will begin to deteriorate leading to progressive declines in temperature.
Alcohol makes a cold person feel warm by dilating peripheral blood vessels. Thus, the core temperature drops. But if the temperatures stay within thermoneutral zone, more blood to periphery makes skin nerves send warm signals to hypothalamus, so we feel warm. If the core temperature drops below the zone, then heat gain mechanisms activate. If we keep drinking, sedation sets in and inhibits the heat gain mechanisms. Therefore, alcohol promotes hypothermia in a cold environment.
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