Epidermis- Composed of keratinized Stratified Squamous Epithelium. Contains several cells that perform a variety of functions including making this a tough protective external layer.

Dermis- Composed of Areolar Connective Tissue in Papillary layer and Dense Irregular Connective Tissue in Reticular layer. Contain fibers and cells that allow strength and the ability to stretch.

Hypodermis- Composed of Areolar Connective Tissue and primarily Adipose Tissue. This subcutaneous layer is critical for insulation and the absorption and storage of nutrients.

Integumentary System- consists of skin and its appendages (hair, sebaceous and sweat glands, and nails). Protects our body from bumps and scrapes, chemicals, harmful microorganisms, water loss, and UV radiation.

Protection- Cushions and insulates deeper body organs and protects from cuts. Protects from chemical microorganisms and UV radiation.

Temperature Regulation- The skins capillary networks and sweat glands regulate loss of heat.

Excretion- Acts as excretory system when urea, salts, and water are lost through sweat.

Production of Vitamin D- Epidermal cells use UV radiation to synthesize Vitamin D.

Sensory Reception- skin contains sensory receptors that are asoociated with nerve endings.

Keratinocytes- Most abundant, produces keratin a tough fibrous protein that gives the epidermis its tough protective properties.

Stem Cells- Can be found in Stratum Basale. Divide and regeneration for growth and renewal of epidermis.

Melanocytes- Produce melanin and protect against UV radiation.

Tactile Epithelial Cells- associated with sensory nerve endings and function as receptor for touch.

Dendritic Cells- Part of Immune System, signal immune response when invaded by foreign microorganisms.