CH. 6 SECTION 3SKIN

Michelle Napier

1. skin -the largest organ of our body- made up of 3 basic layers

2. layers of skin

1. epidermis- outermost layer2. dermis- middle layer3. fatty layer- innermost layer

3. epidermis -cells are dead and water repellant- new cells are produced constantly at the base of the epidermis- produces melanin

4. melanin -pigment that protects skin and gives it its color- this is what makes tanning possible

5. dermis -thicker than the epidermis- contains blood vessels, nerves, muscles, oil, and sweat glands- holds fat

6. functions of the skin

-protection- sensory response- vitamin D formation- helps blood absorb calcium- regulates body temperature- helps the body get rid of waste

7. heat and waste exchange

-blood vessels in the skin expand and dilate which releases heat or holds heat in- as they expand, blood flow increases and heat is released- our skin holds about 3 million sweat glands

8. functions of sweat glands

1. regulate body temperature2. release waste- when vessels dilate, pores on the

skin open and perspiration is released from sweat glands. This allows your body to cool off.

- cells use energy and nutrients and have waste which is released through sweat

9. bruises -blood vessels under the skin burst but skin stays in tact- red blood cells leak into tissues and a chemical called hemoglobin is released- hemoglobin is responsible for the different colors of bruises

10. cut -a tear in the skin- scars are formed when large amounts of tissue build up under a cut

11. skin grafts - pieces of skin cut from one part of the body and put on another part that was injured or burned