Does the epidermis contain root hairs?

1 Answer
Dec 19, 2015

See explanation.


Hair is composed of cornified threads of cells that develop from the epidermis and cover most of the body. Each hair has a medulla, cortex, and cuticle. The medulla in the center contains soft keratin and air. The cortex, the innermost thickest layer, has the pigment that gives hair color. The cuticle, the outermost layer, has cells that overlap like scales. Both the cuticle and cortex have hard keratin.

The hair root in a hair follicle is embedded beneath the skin. The hair shaft protrudes from the skin. Hair sheds and is replaced constantly during growth and rest phases. Hair has a protective function: eyebrows keep sweat from running into the eyes, nose and ear hairs filter dust from the air, and scalp hairs protect against abrasion and overexposure to sun rays.

Hair follicles extend into the dermis; the deep ends expanded parts are called hair bulbs. A papilla (connective tissue protrusion that contains capillaries) protrudes into the hair bulb and provides nutrients for the growing hair. The hair follicle walls have an inner epithelial root sheath and an outer dermal root sheath. The epithelial root sheath has an inner and an outer layer that thins as it approaches the hair bulb. It becomes the matrix, the actively growing part of the hair bulb that produces the hair.