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Skin. Largest Organ?. Skin!!!. Functions of Skin. 1. Barrier against infection. 2. Regulates body temperature. 3. Removes waste products. 4. Protects against ultraviolet light. Epidermis. First layer of skin. Outer cells: dead cells
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Largest Organ? Skin!!!
Functions of Skin 1. Barrier against infection. 2. Regulates body temperature. 3. Removes waste products. 4. Protects against ultraviolet light.
Epidermis • First layer of skin. • Outer cells: dead cells • Inter cells: These are living cells that move up to take the place of the dead cells after they are shed.
Keratin • Fibrous protein that provides a tough covering for the skin.
Melanocytes • Specialized cells in the epidermis. • Produce melanin which gives skin its color.
Melanocyte Melanin Melanocytes
Dermis Job # 1: Temperature Regulation • Sweat Glands: Too Hot!!! A. Produce perspiration: small droplets of water. B. Removal of these drops carries heat away from the body.
Dermis Temperature Regulation • # 2 Blood Vessels A. Too cold! They will constrict and stay away from the skin. B. Too hot! They expand near the skins surface and radiate heat out of the body.
Sebaceous Gland These glands produce a substance called sebum. • This oil spreads out on the skins surface making the skin: • more flexible • and waterproof.
Other things in the Dermis! • Collagen Fibers: for support. • Nerve Endings: for feeling. • Muscle • Hair Follicles
Subcutaneous Layer • Third layer of skin. • This layer is basically made out of fat. • This gives the body insulation and the skin flexibility.
Hair Functions 1. Coverage for exposed areas of the body. 2. Keeps dirt and particles from entering holes in the body (nose, mouth, ears).
Hair Development • Hair is made up of long columns of cells that have died. • These cells fill with keratin and become stiff.
Nails • Areas of cells that fill with large amounts of keratin. • Protect fingertips and toes.