Coat Structure

Hair consists mostly of keratin, the same tough protein that makes up the skins outer layer (epidermis) and the claws, which are technically skin.

Because hair is made mostly of protein, normal hair growth consumes a good percentage of daily protein intake. The surface of a hair consists of overlapping cuticle cells, which point away from the body.

A hair stroked from root to tip feels smooth, while one stroked from tip to root feels rough because of the "lay" of the cells. The cuticle reflects light and helps to give the coat its sheen; a dull coat may signify cuticle damage.

 Hair grows in cycles that are controlled by hormones, length of daylight hours, and the surrounding temperature. Humans have simple follicles: a single, large hair grows from each hair follicle.

Cats have more efficient insulation, in the form of compound hair follicles: up to six primary (guard) hairs grow from each follicle, each surrounded by finer secondary (down and awn) hairs. Each follicle has its own arrector muscle, which can make the primary hairs stand on end.

Cats ''raise their hackles" like this when alarmed or angry, but also to increase insulation and cut heat loss. Cats have two types of hair specialized for sensation.

The whiskers, or vibrissae, are thick, stiff hairs found on the head, the throat, and the forelegs. Other large, single hairs, called tylotrichs, each surrounded by a complex net of blood vessels and nerves, are scattered over the skin and act like short whiskers.