The Skin Chapter 14 Section 4

Key concepts What are the functions and the structures of the skin? What habits can help keep your skin healthy?

Key Terms Epidermis Melanin Dermis Pore Follicle Cancer

Skin performs several major functions Skin covers and protects the body from injury, infection and water loss Helps regulate body temperature, eliminate wastes, gather information about the environment and produce vitamin D

Protecting the body Skin forms a barrier that keeps disease causing microorganisms and harmful substances outside the body Helps keep important substances inside the body-prevents the loss of fluids such as water

Maintaining temperature Help maintain a stead body temperature Blood vessels run throughout the skin, when you become too warm blood vessels enlarge and the amount of blood that flows through them increases This allows heat to move from your body to the outside environment Sweat glands produce perspiration in response to excess heat

Eliminating wastes Perspiration contains dissolved waste materials

Gathering information Skin gathers information about the environment

Producing vitamin D Vitamin D is important for healthy bones because it helps the cells in your digestive system absorb the calcium in your food

Epidermis Outer layer of the skin Thinner than the dermis Does not have nerves or blood vessels Each epidermal cell begins life deep in the epidermis, where cells divide to form new cells New cells mature and move upward After two weeks the cells die and become part of the epidermal surface layer Cells remain in this layer for about two weeks they are then shed and replaced by the dead cells below

Epidermis function Most of the protection provided by the skin is due to the layer of dead cells on the surface Cells deep in the epidermis produce melanin a pigment or colored substance that gives skin its color. The more melanin in your skin the darker it is

Dermis Located below the epidermis and above a layer of fat This fat layer pads the internal organs and helps keep heat in the body Contains nerves and blood vessels Contain sweat glands, hairs and oil glands

Caring for your skin How can you help keep your skin healthy? Eat a healthful diet-well balanced diet provides the energy and raw materials needed Keep your skin clean and dry-wash your skin with mild soap and get rid of dirt and harmful bacteria Limit your exposure to the sun-repeated exposure to the sun can cause cancer