The document discusses the functions and structure of human skin. Skin has several key functions: protection, sensation, temperature regulation, excretion. It protects against microorganisms, ultraviolet light, dehydration and abrasions. Skin detects sensations like hot, cold, touch, pressure and pain. It helps regulate temperature through control of blood flow and sweat gland activity. Skin also helps with excretion of waste and gland secretions. Structurally, skin has three layers - epidermis, dermis and hypodermis. The epidermis is composed of multiple strata and provides protection. The dermis is made of connective tissue. Skin color is determined by pigments, blood circulation and thickness of the outer layer.