How is the mammalian skin adapted/ suited to its function?

-The cornified layer; is made up of dead cells to provide protection against physical/ mechanical damage, prevent entry of pathogens and reduce water loss;
-The granular layer; consists of living cells that give rise to cornified layer;
-Malpighian layer; is made of actively dividing cells that give rise to new epidermis; contains melanin that protects the skin against harmful UV rays and give the skin its dark colour;
-The sweat/ sudorific glands; has secretory cells which secrete more sweat when it is hot. Sweat contains excretory products e.g. excess water, traces of urea, lactic acid, ammonia, mineral salts; sweat evaporates taking away latent heat of vaporization thus cooling the body;
-Blood vessels/ arterioles; nourish the skin cells / supply oxygen and nutrients and remove waste products; they vasodilate when it is hot; more blood flows near the skin surface hence more heat is lost through conduction and convection; when it is cold the arterioles vasoconstrict; less blood flows near the skin surface thus conserving heat;
-Erector pili muscles; contract when it is cold; causing the hairs to stand erect/ upright; hairs trap air which is a poor conductor of heat conserving heat; they relax when it is hot; causing the hair to lie flat on the skin surface hence more heat is lost;
-Hair follicle; is supplied with sensory nerves to increase sensitivity of the skin;
-Sebaceous glands; secrete sebum which keep the hair and epidermis supple and water proof; sebum contains antiseptic substances to protect the skin against bacteria;
-Nerve endings; detect stimuli e.g. pain, pressure, temperature causing the animal to respond appropriately;
-Subcatenous layer/ adipose tissue; is made up of fat/ fat cells to insulate the body against heat loss; contains special cells that manufacture vitamin D when exposed to the sun;