Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Epithelial Tissue
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Body Tissues Just a little reminder…. *Cells are specialized for particular functions *Tissues: groups of cells with similar structure and function I. Four primary types Epithelium – cover & protect Connective tissue - support Nervous tissue – signaling & communication Muscle – movement & contraction
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Where is Epithelial Tissue Found? 1. Body coverings Skin 2. Body linings Body cavities, respiratory tract, digestive tract 3. Glandular tissue Glands Reproductive organs
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings I. What are the Functions of Epithelial Tissue? 1.Protect the tissue they cover. a)against bacterial & chemical damage b)lines respiratory tract with cilia which sweeps debris away from lungs. 2. Regulate gas and nutrient exchange between the organs they cover and body cavities a) Absorption: lines digestive organs and helps absorb food into the body
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings b) Gas exchange: between air sacs of lungs and walls of capillaries c) Filtration: in the kidneys, epithelium filters blood and absorbs 3. Secrete substances such as sweat, oil, hormones, mucus, and enzymes. a)specialty of the glands 4. Provide sensation with the environment.
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings How is Epithelial Tissue Classified? 1.Number of cell layers (first name) a.Simple – one layer b.Stratified – more than one layer
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings How is Epithelial Tissue Classified? 2. Shape of cells on free surface (2 nd name) a.Squamous – flattened b.Cuboidal – cube-shaped c.Columnar – column-like
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings What are Special Characteristics of Epithelial Tissue? 1. Cells fit closely together to form a protective layer. 2. Always have one free surface 3. The cells rest on a layer of cells called a basement membrane 4. Avascular (have no blood supply) *Cells get what they need by diffusion of nutrients through basement membrane. 5. Regenerate easily after damage if well nourished