Core Temperature and Skin Temperature. The temperature of the deep tissues of the body—the "core" of the body—remains very constant, within ±1°F (±0.6°C), day in and day out, except when a person develops a febrile illness. Indeed, a nude person can be exposed to temperatures as low as 55°F or as high as 130°F in dry air and still maintain an almost constant core temperature. The mechanisms for regulating body temperature represent a beautifully designed control system. The purpose of this chapter is to discuss this system as it operates in health and in disease.
The skin temperature, in contrast to the core temperature, rises and falls with the temperature of the surroundings. The skin temperature is the important temperature when we refer to the skin's ability to lose heat to the surroundings.
Normal Core Temperature. No single core temperature can be considered normal, because measurements in many healthy people have shown a range of normal temperatures measured orally, as shown in Figure 73-1, from less than 97°F (36°C) to over 99.5°F (37.5°C).The average normal core temperature is generally considered to be between 98.0° and 98.6°F when measured orally and about 1°F higher when measured rectally.
The body temperature increases during exercise and varies with temperature extremes of the surroundings, because the temperature regulatory mechanisms are not perfect. When excessive heat is produced in the body by strenuous exercise, the temperature can rise temporarily to as high as 101° to 104°F. Conversely, when the body is exposed to extreme cold, the temperature can often fall to values below 96°F.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.