Characteristics of all Epithelial Tissues PDF
Preview Characteristics of all Epithelial Tissues
Characteristics of all Epithelial Tissues 1. Cells are closely associated with little extracellular space 2. Cells are strongly attached via intracellular junctions 3. Line body surfaces and body cavities 4. Specialization - absorption, secretion,sensation, contractility 5. Cells are polarized 6. Epithelial tissues rest on a basement membrane Basement Membrane = Basal Lamina Functions: 1) Structural attachment of epithelial cells to the CT 2) Compartmentalization. Isolate epithelial cells and muscle cells 3) Filtration. Movement of molecules is in part regulated by ionic charges (particularly important in the kidney) 4) Help to maintain the polarity of the epithelial tissues 5) Tissue scaffolding. Helps to scaffold regeneration (example: during nerve regeneration) Composition Proteoglycans, glycoproteins, collagen. A layer of reticular fibers underlies basement membranes Hemidesmosome Zonula Occludens Zonula Adherens Gap Junction Desmosome Basement Hemidesmosome Membranes Hemidesmosome Zonula Occludens Membrane Proteins: Occludin, Claudin Cytoplasmic Proteins: ZO-1, actin, etc. Zonula Adherens α - actinin, vinculin Intercellular Space Actin (15 nm) Cadherins DESMOSOME (MACULA ADHERENS) Desmoplakins I and II, Plakoglobin, Desmocalmin Intercellular Space (25 nm) Contains the Transmembrane Intermediate Proteins Desmocollin Filaments and Desmoglein HEMIDESMOSOME Plaque Contains Tonofilaments BP 200 Plaque TM Contains PM Transmembrane TM Proteins α6 Integrin, BM β4 Integrin and BP 180 Type VII Collagen The Term BP is related to Bullous Phemphigoid
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