Epithelial Tissue Epithelial tissues in the body line body cavities, cover the body surface (skin) and form glands. Functions include: protection of.

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)