ENVELOPES OF THE BODY
Section I. INTRODUCTION
Figure 3-1. The integument and related structures.
The envelopes of the body serve to protect the living structures within the body in
a number of ways. The envelopes are like an air conditioner; they help to remove heat.
The envelopes are like a blanket; they help to retain heat when the surrounding air is
cold. One of the envelopes, the skin, is like a chemical factory; it manufactures vitamin
D in the presence of sunlight. The skin is like an umbrella; it helps to protect us from
the sun and the rain. The skin also protects the body from dehydration and friction.
3-2. ENVELOPES OF THE BODY
a. The human body has three concentric coverings (Figure 3-1), one inside of
the other. The outermost layer is the integument proper (skin). Immediately beneath
the skin is the subcutaneous layer. Beneath this layer is the investing deep fascia, a
membrane which completely covers the remaining structures of the body.