, has the shape of a slender filament; it is composed of keratinized cells
growing from hair follicles that extend deep into the dermis, often projecting into the underlying subcutaneous layer.
Three zones can be recognized along the length of a hair: the hair bulb, root, and shaft. The
consists of epithelial cells and is
a swelling at the base where the hair originates in the dermis. The epithelium at the base of the bulb surrounds a small
which is composed of a small amount of connective tissue containing tiny blood vessels and nerves. The
is the zone of
the hair extending from the bulb to the skin surface. The
is the third portion of the hair that extends beyond the skin surface.
The hair bulb contains living epithelial cells, whereas the root and shaft consist of dead epithelial cells.
15. Briefly describe the functions of hair.