With some religious occasions occurring in one of the hottest months of the year for those of us in the northern hemisphere, and the one of the coldest times of the year for those in the southern hemisphere, our physical ability to handle weather extremes becomes an interesting topic to reflect upon.
Can you imagine the special situation required of our bodies to adapt to extreme changes in weather? How do our bodies handle such changes?
In fact, Allah has provided us with very efficient systems for regulating our internal temperature, automatically maintaining a stable core body temperature in cold winters, warm summers, and wild swings between both extremes.
The normal core body temperature for a healthy human is around 37°C. However, this can vary by as much as +/- 0.6°C depending on the physical activity, metabolism, hormonal levels, and even the time of day.
Adapting to Cold Weather
In cold weather, if the core body temperature drops below 34.4°C, hypothermia occurs. If it continues declining, the temperature regulating system in the hypothalamus usually fails around 29.4°C, with death soon after.
Living in cold locations, humans undergo physical adaptation to increase internal heat production.
As observed by the German biologist Carl Bergmann in 1847, humans in cold regions have greater body mass than those in warm climates.
The process of metabolism, converting food to fuel in our body’s cells, is accompanied by heat production. Therefore, greater body mass is equivalent to more cells, which produce greater heat for protection from cold.
Additionally, Allah provides other long term physical adaptations to cold, including increased basal metabolic rate, as well as heat-insulating fat surrounding vital organs. Changes in blood flow patterns are also noted among people living in cold climates.
In the short term, as when a sudden, drastic change in location to a cold climate occurs, physical acclimatization has also been wondrously designed into our body systems by Allah to protect us in this case.
Sensing a drastic change in climate, our bodies respond to protect core body temperature. First, vasoconstriction occurs, narrowing blood vessels near the skin’s surface.
By reducing blood flow to areas in closest contact with the cold, less heat is lost through radiation. However, if temperatures are below freezing, our bodies won’t maintain vasoconstriction, because frostbite would occur.
Consequently, the internal temperature system responds with vasodilation, dilating these same blood vessels, increasing warm blood flowing near the skin to protect from freezing.
Cycling continuously between vasoconstriction and vasodilation, the body attempts to protect both stable core body temperature, and skin from freezing.
Shivering, a natural increase in small muscle activity also helps produce heat.
