A & P

• 1. Epithelial tissue
• 2. Connective tissue
• 3. Muscle tissue
• 4. Neural tissue

Epithelia form the surface of the skin and line the digestive, respiratory, reproductive and urinary tracts--the line all passageways that communicate with the outside world.

• 1. Cellularity- composed almost entirely of cells bound closely together by interconnections called cell junctions.
• 2. Polarity- there are structural and functional differences between the exposed and attached surfaces.
• 3. Attachment- the base is bound to a thin basal lamina
• 4. Avascularity- meaning they lack blood vessels.
• 5. Regeneration- cells that are damaged or lost at the exposed surface are continuously replaced through stem cell divisions; rate of regeneration is much higher in epithelia than any other tissues.

• 1. Provide physical protection- from abrasion, dehydration and destruction by chemical or biological agents.
• 2. Control permeability- any substance that enters or leaves your body must cross an epithelium.
• 3. Provide sensation- sensory nerves continually provide information about the external and internal environments.
• 4. Produce specialized secretions- epithelial cells that produce secretions are called gland cells.