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Unformatted text preview: Chapter 3: Histology Epithelial Tissue- Covers surface, lines vessels, organs, ducts, forms glands- Very extensive- Characteristics o Cellularity (little matrix): consists of tightly packed cells o Specialized junctions (i.e., tight, desmosomes) Tight junction : membranes actually come together; tightest but not the strongest (bladder: nothing can escape) Intracellular space is completely occluded Adherens junction : PM comes together; stronger connection Adhesion belt: extensive area of cytoplasm Actin (microfilament): reinforcing rods, make up adhesion belt Desmosome : heaviest and strongest of all Plaque is more abundant and heavier Protein rods are intermediate filaments (keratin) Hemidesmosome: has all the same components of desmosome but only on one side Gap junctions: no plaque or protein rods, and although they have protein rods, they are called connections and are tubular creating a pathway from one cell to the next; seen in heart o Apical surface: free or unattached Epithelial will always have one side of its tissue not attached to anything else The other side will be attached to a hemidesmosome Basement membrane: formed by secretions o Avascular (basement membrane: basal lamina and reticular lamina) No direct blood supply to the epithelium o Thoroughly innervated o Highly regenerative: always repairing- Epithelial Tissue Types o Simple: 1 layer o Stratified: 2 or more o Pseudostratified: 1 but appears to be 2 Cell Types- Squamous: flat, central nucleus o Simple squamous : simplest, most delicate...
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- Spring '08