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→Hair Types
*'''Guard hairs'''
*'''Guard hairs'''
These are generally stiff and straight and form the outer haircoat of an animal. They are uniformly distributed across the skin surface and give the haircoat a smooth appearance. The smoothness of the coat is important in allowing rain to fall from the surface without penetrating deeper to the epidermis and causing loss of body temperature. The oily coating of the haircoat comes from the secretions of the sebaceous glands in the epidermis, associated with the hair follicle. This also contributes to the ‘waterproofing’ of the haircoat. Each hair consists of an outer cuticle, with a cortex and innermost medulla. It is composed of highly keratinised, dead epithelial cells, with the arrangement into the 3 layers conferring flexibility.
These are generally stiff and straight and form the outer haircoat of an animal. They are uniformly distributed across the skin surface and give the haircoat a smooth appearance. The smoothness of the coat is important in allowing rain to fall from the surface without penetrating deeper to the epidermis and causing loss of body temperature. The oily coating of the haircoat comes from the secretions of the sebaceous glands in the epidermis, associated with the hair follicle. This also contributes to the ‘waterproofing’ of the haircoat. Each hair consists of an outer cuticle, with a cortex and innermost medulla. It is composed of highly keratinised, dead epithelial cells, with the arrangement into the 3 layers conferring flexibility.
[[image: Section of mature hair follicle.jpg|thumb|250px|right|LS of a mature hair follicle in the lip of a cat. Copyright RVC2008]]
The '''''arrector pili''''' muscle is attached to the proximal end of the follicle and the dermis close to the point at which the hair is externalised. Involuntary contraction of this muscle in cold ambient temperatures causes erection of the hairs to trap warm air against the skin, thus providing insulation. This can also be induced by the ‘fight or flight’ mechanism of the '''sympathetic nervous system'''.
The '''''arrector pili''''' muscle is attached to the proximal end of the follicle and the dermis close to the point at which the hair is externalised. Involuntary contraction of this muscle in cold ambient temperatures causes erection of the hairs to trap warm air against the skin, thus providing insulation. This can also be induced by the ‘fight or flight’ mechanism of the '''sympathetic nervous system'''.