surface of the epidermis form a thin layer of flattened, dead cells. 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 producemelanin. Melaninis 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 is fed by diffusion from the blood vessels of the dermis.
Dermis
Thedermisis the layerof skin directly under the epidermis. It is made of a tough connective
tissue that contains the proteincollagen. Collagenis a long, fiber-like protein that is very
strong. The dermis is tightly connected to the epidermis by a membrane made of collagen
fibers. As you can see inFigure16.6, the dermis contains the hair follicles, sweat glands,
oil glands, and blood vessels. It also holds many nerve endings that give you your sense of
touch, pressure, heat, and pain. Tiny muscles in the dermis pull on hair follicles which cause
hair to stand up. This can happen when you are cold or afraid. The resulting little “bumps”
in the skin are commonly calledgoosebumps, shown inFigure16.7.
Figure 16.7: Goose bumps are caused by tiny muscles in the dermis that pull on hair follicles,
which causes the hairs to stand up straight. ( 23 )