The human body perform countless chemical reactions that are essential for life every second. Many of these reactions can only be performed within a limited temperature range. As a result, humans have a variety of mechanisms to keep their body temperature within a constant range.

Several common childhood diseases can cause fever and a splotchy rash on the face. Most of the time, these simple illnesses go away on their own, but occasionally a rash and fever requires the care of a doctor.

A fever, headache and muscle aches are all symptoms of the common cold. The common cold affects billions of Americans each year, according to the National Institute of Allergy and Infectious Diseases. The common cold is the most prevalent during the winter months and children are at a higher risk of getting a cold.

Your child has a fever when she has a rectal or ear temperature of 100.4 degree Fahrenheit or greater, an oral temperature of 100 degrees Fahrenheit or greater or an axillary -- underarm -- temperature of 99 degrees Fahrenheit or greater. Taking a temperature in the ear in a child under 6 months of age is not reliable.

A normal temperature for a toddler is 98.6 degrees or slightly higher. A fever of 104 degrees indicates a medical problem that should be evaluated by a physician. Rarely, a child with a fever of 104 degrees will have a seizure due to the increased temperature.

Vigorous exercise boosts your body's heat production and can increase your body temperature by several degrees.

Buffer systems, whether inside your body or not, help to control the acidity of a solution. In your body, this is particularly important, as you need a very stable environment both inside and outside the cells with regard to temperature, acidity and other variables.

A slightly higher than normal body temperature is common during pregnancy because of the hormone progesterone and increased metabolism. On the other hand, an infection or illness can cause your body temperature to increase too much, causing harm to you and your unborn baby.

The baseline core temperature for most humans is 98.6 degrees Fahrenheit. Your body temperature fluctuates throughout the day depending on physical activity, body heat loss and environmental factors.

The human body maintains a consistent core temperature between 98 and 100 degrees Fahrenheit, and it requires certain nutrients, including water and magnesium, to maintain this healthy temperature. Dehydration can hinder the body’s ability to maintain a safe temperature.

Maintaining your body temperature is a function of your metabolism -- specifically your basal metabolic rate, or BMR. Your BMR is the amount of calories you burn at rest and can account for between 50 and 80 percent of all the energy you use.

According to California Pacific Medical Center, most viral fevers range between 101 degrees and 104 degrees and disappear after two or three days. A fever of 103.5 degrees Fahrenheit technically sits on the border between a common fever and a high fever.