Integumentary System

1. Integumentary System

2. Your skin is made up of three layers of tissue • Epidermis: the outer, thinnest layer of skin • Outermost cells are dead and repel water • New cells are constantly being made to replace the dead cells • Dermis: the later of skin cells right below the epidermis • Contains many blood vessels, nerves, muscles, and oil and sweat glands • Fatty layer: below the dermis which helps keep the body from getting too hot or too cold • When a person gains weight, much of the fat is stored in this fatty layer Skin Structures

3. Melanin: a pigment that protects your skin and gives it color • Different amounts of melanin produced by cells result in differences in skin color • The more melanin present, the darker the color • When your skin is exposed to ultraviolet (UV) rays, more melanin is made • Light skin tone burn more easily • Greater risk of melanoma, the most serious form of skin cancer Skin Colors

4. Protection • Skin is a protective covering over the body that prevents physical and chemical injury • Stops some bacteria and other disease-causing organisms from passing through unbroken skin • First line of defense • Skin slows down water loss from body tissues Skin Functions

5. Sensory Response • Special nerve cells in the skin are able to sense things • Sends information to the brain • How you can sense the softness of a cat or the heat of a pan Skin Functions

6. Formation of Vitamin D • In the presence of UV light, a fatlike molecule in your epidermis produces small amounts of the vitamin • Vitamin D is needed for good health because it helps your body absorb calcium from the food you eat Skin Functions

7. Control of Body Temperature • Blood vessels in the skin can help release or hold heat • Dilated (expanded) blood vessels cause blood flow to increase and heat is released • Constricted (smaller) blood vessels cause blood flow to slow and less heat is released • Dilated blood vessels give you a flushed red appearance Skin Functions

8. Ridding the Body of Wastes • Adult humans have about three million sweat glands • Help control the body’s temperature and get rid of wastes • As blood vessels dilate, pores open in the skin that lead to the sweat glands • Sweat moves out onto the skin; heat transfers from the body to the sweat on the skin; the sweat evaporates and the heat is removed • As your cells use nutrients for energy, they produce wastes • Sweat glands release water, salt, and other wastes Skin Functions

9. Include bruises, scratches, burns, and scrapes • When skin is injured, the epidermis makes new cells and the dermis repairs tears • Injured skin allows disease-causing organisms to enter the body rapidly and an infection could occur Injuries and Repair

10. A bruise happens when tiny blood vessels underneath unbroken skin have burst • Red blood cells from these broken blood vessels leak into the surrounding tissue • The blood breaks down into pigments • This causes the bruised area to turn blue, red, and purple • Swelling may occur Bruises

11. The body can repair bruises and small cuts • When the skin is severely burned or large areas of skin are injured, there may not be enough skin cells left to produce new skin • If the skin is not repaired, water is lost from the skin and muscle tissue • Infection and death can result • Skin grafts are used to treat injuries to large portions of skin • Pieces of skin are cut from one part of a person’s body and moved to the injured or burned area where there is no skin • Over time, the skin graft becomes part of the skin around it Skin Grafts