1. The Skin
Chapter 14
Section 4

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

3. Key Terms
Epidermis
Melanin
Dermis
Pore
Follicle
Cancer

4. 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

5. 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

6. 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

7. Eliminating wastes
Perspiration contains dissolved waste materials

8. Gathering information
Skin gathers information about the environment

9. 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

10. 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

11. 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

12. 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

13. 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