temperature of the blood is continuously monitored by special temperature detectors.
These detectors are located in the hypothalamus of the brain.
b. Peripheral Body Temperature. The temperature of the body surface and
the upper and lower members is called the peripheral body temperature. Peripheral
body temperature can vary widely. Temperature receptors in the body periphery
monitor the peripheral body temperature.
3-29. COUNTERCURRENT MECHANISM
In the limbs of the upper and lower members, the venous blood often has a low
temperature. The return of this non-warmed blood to the core of the body might be
dangerous. However, within the upper and lower members, the deep veins are
generally located adjacent to the major arteries. As the venous blood flows toward the
center of the body, it is gradually warmed by the arterial blood coming from the body.
This condition is called the countercurrent mechanism.
3-30. REMOVAL OF HEAT
By selecting shady or cool surroundings, an individual can avoid becoming
overheated. In other cases, however, the body heat may become excessive. In such
cases, if the body is to remain healthy, the surplus body heat must be removed.
a. Sweating. Sweat (perspiration) is made up primarily of water, with various
substances dissolved in it. As one of its physical characteristics, water has a relatively
high heat-carrying capacity. In addition, it evaporates from the surface of the body.
Another physical characteristic of water is that it removes large numbers of calories
b. Radiation. In addition, heat can be radiated directly from the surfaces of the
body. This is particularly true of the surfaces of the axillae (armpit areas), the inside of
the elbow areas, and the groin. These are areas where the skin tends to be thinner
3-31. CONSERVATION OF HEAT
When the ambient (surrounding) temperature is cool or cold, the body must
conserve heat rather than remove it.
a. Less Sweating. An immediate means of conserving heat is to stop sweating.
(1) In cool surroundings, the superficial capillaries are shut down. Thus,
circulation is limited to the deep cutaneous capillaries. Because of the insulating fatty