1. Skin Functions  Protects deeper tissues  Aids in heat regulation  Aids in excretion of urea and uric acid  Synthesizes vitamin D  Lubricate body surfaces  Sensory receptors 1

2. 2

3. 3 Cell and Layers of the Epidermis

4.  Epidermis – outer layer ◦ Stratified squamous epithelium ◦ Often keratinized (hardened by keratin)  Dermis ◦ Dense connective tissue layer  Hypodermis ◦ Not part of the skin ◦ Anchors skin to underlying organs ◦ Composed mostly of adipose tissue (Subcutaneous fat) ◦ Functions  energy reservoir  thermal insulation  Thickness variable, normally 1-2 mm 4

5.  Scale-like modifications of the epidermis ◦ densely packed cells filled with hard keratin  Growth rate is 1 mm per week  Lack of pigment makes them colorless 5  Free edge  Body  Root of nail