BIOA11H3 Chapter 4: Chapter 4
Document Summary
Groups of similar cell types that perform a common function comprise a tissue. Damage to them can sometimes prevent them from recovering their function. Or epithelium tightly packed sheets of cells that cover organs and outer surfaces, as well as line hollow organs, vessels, and body cavities. Not attached on all surfaces they are anchored on one face of the tissue but free on the other tissue face. Unattached tissue can be exposed to body fluids or the external environment. E. g. epithelium tissue that lines blood vessels is attached to the wall of the blood vessel, but its outer surface is exposed to the bloodstream. Epithelium that comprises the outer layer of skin anchored to the underlying tissue but has a surface that is exposed to air. Also true to respiratory surfaces, digestive, urinary and genital tracts it can be a single layer of many thick layers. Epithelia cells function in protection, secretion and absorption.
