Explain the role of the skin in thermoregulation.

(i) Hair shaft;

• During cold conditions – the Erector pili muscle contracts raising the hair shaft/hair erect. The hair traps air which insulates the body.
• During hot conditions – the erector pili muscles relax hence the hair shaft lies on the skin. Little or no air is trapped. Hence heat is lost through convection /conduction /radiation;
• (ii) Blood vessels
• During cold conditions – -the blood vessels vasoconstrict hence less blood flows near the skin surface to minimize heat loss through conduction/convection/ radiation;
• During hot conditions – the blood vessels vasodilate. Hence more blood flows near the skin surface leading to heat loss through conduction /convection/ radiation;
• (iii) Sweat gland
• During hot conditions – sweating occurs and as the sweat evaporates heat is lost in form of the latent heat of vaporization cooling the body;
• During cold conditions – sweating reduces; hence heat is retained in the body.
• (iv) Subcutaneous fatty layer /Adipose tissue
• Insulation of the body;