1. Epithelial Coverings
Body armor

2. Epithelial coverings
In Vertebrae skin functions in protection and temperature regulation
In fish, reptiles, and a few mammals the epithelium forms scales
Several types of specialized glands
Mammary glands
Sebaceous glands
Sweat glands

3. Epithelial coverings Skin produces many different structures
Skin of birds produce or form feathers.
Skin of mammals form hair, nails, or claws

4. Epidermis Waterproof layer Deepest layer is the Stratum basale
Site for new skin cell production
Some of these cells produce melanin
Upper layer known as stratum corneum
Cells in this layer are keratinized
Keratin waterproofs skin and makes up hair and nails

5. Dermis Contains blood vessels and other structures
Collagen strengthens the skin yet allows flexibility
Elastin gives skin its elasticity. Fibrous scleroprotein found in elastic tissues such as walls of arteries.
The dermis contains
Sensory receptors
Sweat glands
Oil glands
Hair follicles are embedded in it

6. Hypodermis Located at the base of the dermis
This is a fatty layer important for insulation (white fat).
Infants, hibernating animals, and small rodents that live in cold areas have brown fat.
Brown fat produces heat

7. Disorders of skin
Athletes foot
Impetigo
Psoriasis