The skin covers the external surface of the bodv.
form- iπg a complete barrier against the external environment. It is perforated by various natural openings, e.g. the mouth and the anus, and at these points it blends with the mucous membranes lining the openings.The functions of the skin are:
1.
Protection - it protects the underlying structures of the body and in specialised thickened regions of the skin, e.g. pads of the feet, it gives added protection against physical trauma. It also acts as a physical barrier to protect against invasion by microorganisms and sebaceous glands secrete an antiseptic sebum onto the surface. T he skin also acts as a water barrier as it is almost impermeable to water, preventing the body from drying out or from becoming waterlogged, e.g. when swimming. Pigmented areas in the skin and hair protect against damage from ultπιviolet radiation.2. Sensorg - the surface of the skin is well supplied with many types of sensory nerve endings to detect temperature, pressure, touch and pain. This assists the body in monitoring its external environment.
5. Secretion - a range of glands within the skin produce secretions directly on to the skin’s surface. These include sebum - produced by sebaceous glands: sweat - in the cat and dog sweating only occurs from active sweat glands of the footpads and nose: pheromones - pπxiuced by specialised skin glands.
4. PrYxfuction - ultraviolet light from the sun converts 7-dihydrocholesterol present in sebum into vitamin I). This is activated within the kidney and liver and increases the uptake and metabolism of dietary calcium.
5. Storage - fat is stored under the skin as adipose tissue or subcutaneous fat. Fat is an energy store and also acts as a thermal insulating layer.
6. Thermoregulation - the skin prevents heal loss by diverting blood away from the surface by vasoconstriction, by erecting the hairs to Inip a layer of insulating air. and by having an insulating layer of fat. Heat can be lost from the Ixxiy when required, e.g. by the pπxiuclion of sweat. However, the skin only plays a minor role in heat loss in the dog and cat as they only have active sweat glands in their footpads and nose. Most of the dissipation of excessive body heat in dogs and cats occurs via panting.
7. ConHnuninition - pnxluction of pheromones, which are natural scents used for intraspecific communication. Other ‘scents’ produced for communication arc those of the circumanal glands and glands of the anal sacs. T he integument also provides a means of visual communication, e.g. a dog raises its hackles when threatened, which is seen as a warning of possible aggression.