Skin
Structure
Two layers
1. Epidermis composed of layers of tightly packed epithelial cells
- outer layer is made of tough epithelial cells that have produced
keratin
- keratin is a tough waterproofing protein that protects the dermis
2. dermis is made up of elastic connective tissue
- supports the skin and binds it to muscle & bone
- holds blood vessels, lymph vessels, nerves, sense receptors,
sebaceous glands, sweat glands, & hair follicles
- beneath the dermis there is adipose tissue
sebaceous glands produce oily substance to…
protect the skin & hair
keep them
sweat glands produce sweat through the pores
Function
 keeps microorganism & foreign material from entering the body
 waterproof layer keeps the body from drying out
 excretes a small amount of urea & salts in sweat
 removes excess heat by
- blood vessels widening up & increasing blood flow to the skin’s
capillaries
- sweat evaporates to cool off the body
 retains heat by narrowing blood vessels & reducing blood supply to the
skin capillaries
Standards: 10e