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Hot or Cold? 5 Facts About Your Body Temperature

Most of us are familiar with the number 98.6°F. It’s common to view it as the normal body temperature. It’s actually an average of normal body temperatures.

Your normal temperature may differ by as much as a degree. And your body temperature can routinely change by a degree during the day. Temperatures taken orally, rectally, under the arm or in the ear will vary a bit, too. A temperature taken rectally is the most accurate.


1. What’s a Fever?

When our bodies are fighting a problem such as an infection, our body temperature can go up. The fever is the body’s way to fight the infection.

  • Fever for a child — a rectal temperature of 100.4°F or higher.
  • Fever for adult fever — an oral temperature above 100.4°F or 101°F taken rectally or in the ear.

If a family member runs a fever, contact your health care provider for the appropriate steps to take.


2. How Does the Body Regulate Your Temperature?

The body’s temperature control center is the hypothalamus. It’s a small part of the brain that controls a number of functions. It helps balance body fluids and your salt concentrations. It coordinates the autonomic nervous system — that’s the system that controls processes you don’t have to think about, such as breathing, your heartbeat, blood pressure, digestive processes and your temperature.

The hypothalamus also controls chemicals and hormones that have a role in your body temperature.

The hypothalamus is a bit like a thermostat. It works with the autonomic nervous system to track your body temperature and keep it in the appropriate range.

The system can respond to internal and external influences and make adjustments to keep your body within a degree or two of your normal.

The hypothalamus and your autonomic nervous system work with your skin, sweat glands, muscles and even your blood vessels to keep your temperature normal. 


3. How Does Your Body’s Air Conditioning Work?

Since we’re mammals, we’re warm blooded. Most all of our cells create a bit of heat. Most of our body heat is created in organs such as the liver, brain and heart. Our muscles create a lot of heat, especially when we’re active.

Your hypothalamus and autonomic nervous system continuously adjust a number of complex activities in your body so your body temperature is typically near your normal.

When you get hot, your hypothalamus and nervous system prompts the sweat glands to do their work. The sweat glands draw the water from your dermis. That’s the middle layer of your skin and where much of your body’s water is stored. Your sweat causes evaporative cooling on your skin surface.

Salt is part of sweat because of the way your body moves the water from your dermis into the sweat glands. Because of this, you can lose salt and need to replace it along with water if you are sweating profusely.

If the humidity is high, that means there’s more moisture in the air. This moisture slows the evaporative effect of sweat, which reduces the cooling effect of sweat. This reduction in evaporative cooling is why you may feel hotter on humid days. On humid days your body will likely sweat even more to try to compensate.

On hot, humid days, drinking lots of water will replace the water you lose through the extra sweating.

Keep in mind, when you feel thirsty, you’re already dehydrated. If you work or are physically active outdoors on hot, humid days, plan to drink four cups of water every hour (this is the OSHA recommendation when the heat index is 103° to 115°F).

Another way your body cools itself is by directing more of your blood to flow nearer to your skin. This cools your blood by releasing heat from your blood through the skin.

You may notice someone’s face getting red when they’re hot. That’s part of the body’s effort to shed excess heat.

Heat loss can be increased by up to four times using the blood and as a sort of radiator.

You may have a mattress or pillow that feels cool. These products take advantage of another of the body’s cooling techniques — conduction. This is the same cooling you feel when you’re in a cool swimming pool or lake.

If your body is pushed out of its normal temperature by heat, you could suffer from cramps, heat exhaustion or heatstroke. Be aware of how to prevent and recognize these conditions.


4. How Does Your Body’s Heater Work?

There are times when it’s cold and your body’s furnace needs to take steps to keep you at your normal temperature. It has some tools to generate more heat.

We all know shivering. That’s your body using the heat generated by active muscles to boost your temperature. You can supplement shivering when cold by getting up and moving around. The more you move, the warmer your body will feel.

Your nervous system will also boost heat production in your heat-making organs. Your body will also burn more fuel in your cells to create heat. The typical high-fat diet of people who live is colder climes helps fuel their bodies’ internal furnaces.

To reduce heat loss from your blood, blood vessels near your skin will contract and reduce blood flow and heat loss through your skin. More of the blood is kept in your warmer interior (i.e. your torso).

When you’re exposed to cold, you can suffer from frostbite or hypothermia. Know how to prevent and recognize these conditions.


5. How Can You Help Your Body’s Temperature Control?

What you wear goes a long way toward maximizing the efficiency of your body’s air conditioning and its furnace.

In hot weather, loose-fitting, light colored clothing is a good choice. A good hat to protect your head and shoulders from the sun is advisable. And remember your sunscreen.

Lots of garments with performance-fabric are marketed for use by athletes. If you’re interested, experiment with some different garments and fabrics. Use your best judgment to decide if you feel they enhance your comfort.

In cold weather, it’s hard to beat thoughtfully chosen, layered clothing for comfort and freedom of movement.

If you do run into problems with heat- or cold-related injuries, see your health care provider or visit an urgent care clinic. Heat and cold can both result in significant, even life-threatening health concerns.

Aurora Health Care is a not-for-profit health care organization helping families in Wisconsin and Illinois live well.

Meet the Author

Vanessa L Abejuela-Matt, DO is a family practice physician at the Aurora Health Center in Racine, WI

Read more posts from this author

The information presented in this site is intended for general information and educational purposes. It is not intended to replace the advice of your own physician. Contact your physician if you believe you have a health problem.

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