ANATOMY AND PHYSIOLOGY OF THE INTEGUMENTARY SYSTEM
a. The integumentary system, consisting of the skin and its derivatives, is the
largest and one of the most complex systems of the body. The surface area of the skin
covers about 1.8 square meters (19.4 square feet) of the body of the average male
adult. The skin weighs about six pounds and receives roughly one-third of all blood
circulating through the body. It is difficult to think of the skin as a system, but it is a
complex of organs (sweat glands, oil glands, and so forth). It is elastic, regenerates,
and functions in protection, thermoregulation, and sensation.
b. The protection, sensations, secretions, and the other functions which the
integument gives to the rest of the body are essential for life. Changes in the normal
appearance of the skin often indicate abnormalities or disease of body function. As a
medical non-commissioned officer (NCO), you need to recognize changes in skin
appearance that your treatment might affect. A basic knowledge of the normal anatomy
and physiology of the integumentary system is essential to your job.
LAYERS OF SKIN
a. General Information. Skin consists of three distinct layers: the epidermis,
the dermis, and the subcutaneous layer (figure 1-1). The top layer, the epidermis, is
attached to the second layer, the dermis. The dermis is thick, connective tissue.
Individuals with thick skin have a relatively thick epidermis. Persons with thin skin have
a thin epidermis. The subcutaneous layer, the third layer of skin, is located beneath the
dermis and consists of areolar (minute spaces in tissue) and adipose (fat) tissues. The
first skin layer is fixed to the second skin layer as though the two were glued together.
The second and third skin layers are attached in a different way. Fibers from the
second layer (the dermis) extend down into the third layer (subcutaneous), anchoring
the two layers together. The third layer is firmly attached to underlying tissues and
organs of the body.
(1) The epidermis is composed of stratified, squamous (scale-like), epithelial
cells which are organized in four or five layers. The number of cell layers depends on
the location of the skin on the body. The epidermis has five layers on the palms of the
hands and the soles of the feet because those areas have more wear and tear. Skin on
other parts of the body has four layers of epidermis because there is less exposure to
(2) These are the layers of the epidermis (figure 1-2) from the deepest to
the most superficial.