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With the arrival of chilly conditions, and even snow in some areas, comes the need for the human body to contend with the potentially harsh effects of bitter cold weather.
As you take the appropriate measures, including bundling up in thicker clothing, your body’s built-in system is also working to keep you warm.
Just as sweat helps to cool you off in the sweltering summer heat, the body reacts to the decline in temperature to preserve as much of its heat as possible.
“Probably the most important mechanism is your behavioral adaptation, meaning that when your body starts feeling that it’s getting cold, your brain tells you either to get out of the cold or to do something that will make you warmer, like put warm clothes on or increase your activity,” said Dr. Daniel Bachmann, emergency medicine physician at The Ohio State University's Wexner Medical Center.
The body reacts to the colder conditions in the following five ways.
1) Conserving heat to vital organs
One of your body’s first reactions to the cold is working to contain warmer blood to your chest, abdominal cavity and your brain.
The body must work to maintain its internal core temperature of 98.6 degrees Fahrenheit, or 37 degrees Celsius.
When the temperature drops, thermoreceptors in your skin send an alert to your brain’s hypothalamus, which is the part of the brain that regulates the body’s temperature.
If your skin’s temperature dips below 98.6 F (37 C), the hypothalamus triggers responses including tightening blood vessels in your extremities, which decreases blood flow to the skin and thus decreases heat loss from the skin.
It’s referred to as peripheral vasoconstriction.
“That helps contain warmer blood to the vital organs, but it also puts your extremities at increased risk from the cold,” Bachmann said.
This is why your hands and feet may feel cold much quicker in cooler weather than other parts of your body.
2) Increased need to urinate
As vasoconstriction occurs during colder conditions, more fluid becomes concentrated within your core.
The reduced blood flow to your skin and extremities can make your blood pressure increase, because the same amount of blood in your body is simply being pumped within a smaller space in order to protect your vital organs.
As a result, the kidneys start filtering out the blood’s excess fluid, which reduces the blood’s volume and pressure, according to Arkansas Urology.
Because the fluid needs somewhere to go, you’ll feel an increased urge to urinate.
3) You shiver
You may notice that your body shivers and your teeth chatter when exposed to the cold after a while. Shivering is one of the body’s ways of trying to increase heat production.
“When we feel too hot, we sweat and when it’s too cold, we shiver; this is the signaling from our hypothalamus that triggers these actions,” said Dr. Jagdish Khubchandani, associate professor of community health at Ball State University.
Shivering, which burns up to five times the energy of a resting body, typically begins when the body’s temperature drops below about 95.9 F, or 35.5 C. Involuntary shivering helps increase your metabolism, according to Bachmann.
“That’s just fine muscle movement, which burns some calories, and a by-product of burning calories is heat,” Bachmann said.
4) Skin turns white and hard
If parts of the body aren’t properly protected in freezing temperatures, there is a risk of tissue damage.
“The prime example of that is frostbite,” Bachmann said.
Body parts including the nose, cheeks, fingers and toes are particularly susceptible, due to the decreased blood flood flow in those areas resulting from vasoconstriction.
Frostbite can occur in just five minutes if the conditions are frigid enough.
5) Organ function declines
“Excessive exposures [to the cold] can cause hypothermia, a state of low internal temperature where judgment can be clouded, responses can be sluggish, and slow pulse and breathing, slurred speech and excess shivering and death [can occur] if not treated in a timely fashion,” Khubchandani said.
Once your core temperature drops into the low 90s or high 80s F, brain function and conscious responses will become impaired, according to Bachmann.
As the body continues to get colder, the temperature can also impact the function of other organs.
“The heart is the next most sensitive organ,” Bachmann said. “It’s specifically the electrical signals that cause your heart to beat in a synchronized manner.”
When those electrical signals get disrupted, it can cause cardiac dysrhythmias, or abnormal heartbeats.
For more safety and preparedness tips, visit AccuWeather.com/Ready.
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