pressures become greater as one goes inferiorly in the body. Accordingly, the fascia
becomes thicker to withstand the increasing pressures.
3-25. INTERMUSCULAR SEPTA
a. In the limbs of the upper and lower members, dense FCT membranes extend
from the underside of the investing deep fascia to the bones. The membranes are
known as the intermuscular septa. They divide the space within the investing deep
fascia into discrete muscular compartments.
b. Each muscular compartment is a hydrostatic chamber. In a normal healthy
human being, each compartment is full. Therefore, as arterial blood flows into a
compartment, hydrostatic pressures are created which assist the flow of blood in the
venous vessels back to the heart.
Section VII. BODY TEMPERATURE CONTROL
In order to function properly, the human body must be maintained within a
relatively narrow range of temperature.
3-27. SOURCES OF BODY HEAT
Body heat is derived from several sources.
a. Muscle Contractions. Muscle contractions produce a significant amount of
heat. If muscles were very efficient, they would produce energy in the form of
contractions and very little heat. Since muscles are inefficient, they produce much heat
as they contract. For example, during strenuous physical exercise, the body
temperature tends to rise by several degrees.
b. Metabolic Activity. Another source of heat in the body is certain organs
such as the brain, liver, and so forth. These organs produce heat during their metabolic
c. Solar Radiation. Another source of body heat is solar radiation. When
received in excess, solar radiation can cause sunstroke.
3-28. TYPES OF BODY TEMPERATURE
a. Core Temperature. The core temperature is the temperature within the body
proper. Normally, the core temperature is maintained within narrow limits. The core