Major Functions of Human Skin

Lesson 12 AYL Question 3: List and describe five major functions of the human skin. Describe an event in your life that relates to each of these major functions.

Skin and its accompanying structures compose the integumentary organ system in humans. Skin is a tissue membrane and exists as two layers, the epidermis and the dermis. Its many functions are to protect the body from dehydration, injury, and invasion of bacteria and viruses. It also regulates body temperature, provides sensory information, and produces an inactive form of vitamin D. Specific instances of how the skin reacts in these situations, provides an understanding of how important the skin and its functions are to human wellbeing.

The epidermis of the skin exists as layered squamous epithelial cells. These cells are frequently replaced as cells at the bottom of the epidermis divide and move the older cells to the surface. The dermis consists of dense connective tissue with collagen, elastic, and reticular fibers within a ground substance of water, proteins, and polysaccharides. These fibers give strength and elasticity to the skins structure. Two cell types found in the epidermis are keranocytes and melanocytes. The skins ability to protect the body from dehydration is from the presence of the keranocytes. These cells (often called basal cells) divide at the base of the epidermis and secrete a protein called keratin. They move upward toward the surface of the skin and eventually die, which creates a waterproof layer that maintains the hydration of the underlining cells. Melanocytes in the epidermis produce melanin that is a darkish pigment, which functions as a protection from ultraviolet radiation from the sun. Melanocytes in the skin are most active during exposure to sunlight.

Skin functions as a protection from injury as well as invasion from bacteria and viruses. Tightly compacted keranocyte cells prevent bacteria and viruses from entering the body. Injuries such as blisters, cuts, and scrapes are a pathway for bacteria and viruses to enter the body, leaving it more susceptible to infection. When an injury damages the tissue, cells react by increasing cell division to build back the tissue that promotes healing. Initiation of the immune system accounts for an increase in white blood cells that fights off the harmful bacteria or virus. The regulation of body temperature is an important role of the skin. When a human’s exposure to extreme temperatures occurs, the body can maintain its internal temperature and experience little change. If the body is in a hot environment, the blood vessels dilate and the sweat glands in the dermis produce sweat that releases heat. If the body is in a cold environment, the blood vessels at the surface of the skin constrict, which results in muscle contraction and shivering. This action conserves or produces heat in the body.

Skin contains many sensory nerve endings that work