Epithelial Tissue Epithelial tissues in the body line body cavities, cover the body surface (skin)...
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Transcript of Epithelial Tissue Epithelial tissues in the body line body cavities, cover the body surface (skin)...
Epithelial Tissue
Epithelial tissues in the body line body cavities, cover the body surface (skin) and form glands.
Functions include: protection of body parts (skin) absorption of materials (stomach lining) filtration (kidneys) secretion (mucus cells)
Epithelial TissueCharacteristics of epithelial cells/tissue:fit closely togetherfree surface that doesn’t attach to anythingbottom cells sit on a basement membraneavascular (no blood supply)regenerate easily
Epithelial TissueClassification: each epithelial tissue has two names that indicate (1) the number of layers and the (2) shape of the cells.
Number of layers:Simple - one layer of
cells resting on the basement membrane
Stratified – more than one layer of cells
Epithelial TissueClassification: each epithelial tissue has two names that indicate (1) the number of layers and the (2) shape of the cells.
Shapes of the cells:squamous – flat, platelike cellscuboidal – cube-shaped cellscolumnar – column-shaped cells
Epithelial Tissue: Exceptions
Pseudostratified:single layer of columnar cells of different sizeall cells rest on the basement membranesome cells do not reach the free surfacemodified versions have cilia (free surface)
Epithelial Tissue: Exceptions
Stratified squamous:basal cells are cuboidal or
columnarsurface cells are squamous
Epithelial Tissue: ExceptionsStratified cuboidal & columnar:only two cell layers outermost cells are the indicated shape
Epithelial Tissue: ExceptionsTransitional:basal cells are cuboidal or columnarcells at the free surface are various shapes that
stretch to accommodate liquid volume (bladder)
Epithelial Tissue: GlandularGlandular tissue: epithelium that makes up glands (secretions)
Two types:Endocrine (ductless glands that secrete
hormones directly into the blood stream)Exocrine (attached to ducts; secretions empty
into ducts)