1.3. Skin http://www.ck12.org
Two different layers make up the skin—the epidermis and the dermis (Figure1.5). A fatty layer lies under the
dermis, but it is not part of your skin.
FIGURE 1.
Skin is made up of two layers, the epider-
mis on top and the dermis below. The
tissue below the dermis is called the hy-
podermis, but it is not part of the skin.The Epidermis
Theepidermisis the outermost layer of the skin. It forms the waterproof, protective wrap over the body’s surface.
Although the top layer of epidermis is only about as thick as a sheet of paper, it is made up of 25 to 30 layers of cells.
The epidermis also contains cells that produce melanin. Melanin is the brownish pigment that gives skin and hair
their color. Melanin-producing cells are found in the bottom layer of the epidermis. The epidermis does not have
any blood vessels. The lower part of the epidermis receives blood by diffusion from blood vessels of the dermis.
The Dermis
Thedermisis the layer of skin directly under the epidermis. It is made of a tough connective tissue. The dermis
contains hair follicles, sweat glands, oil glands, and blood vessels (Figure1.5). It also holds many nerve endings
that give you your sense of touch, pressure, heat, and pain.
Do you ever notice how your hair stands up when you are cold or afraid? Tiny muscles in the dermis pull on hair
follicles which cause hair to stand up. The resulting little bumps in the skin are commonly called "goosebumps"
(Figure1.6).