CBNS 101 lecture12

CBNS 101 lecture12 - The Extracellular Matrix Tissues in...

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The Extracellular Matrix
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Tissues in animal cells display two architectural extremes. Epithelial tissues Connective tissues Epithelial sheets line all body cavities. The cells tightly adhere to one another via anchoring junctions. There is limited extracellular matrix and cells themselves bear mechanical stress. Mechanical strength and specialized functions provided primarily by the extracellular matrix. Specialized cell types secrete the matrix and form few permanent attachments.
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Four families of CAMs Cadherins Ig- superfamily Selectins Integrins
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Different CAMs cooperate to mediate the transient adhesive and cell signaling interactions that underlie many important physiological responses. Example-- INFLAMMATORY RESPONSE Normally, neutrophils/leukocytes circulate in blood system. In response to tissue damage or infection leukocytes traverse the endothelial blood vessel wall and migrate to the site of trauma. There they ingest foreign or damaged cells, producing pain and swelling .
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So….What if you’re ready to settle down and develop some permanent attachments? Transient adhesive interactions mediated by CAMs can be stabilized to form specialized cell junctions that link cells together and to the extracellular matrix Occluding junction Anchoring junction Anchoring junction Communicating junction Anchoring junction
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Multiple types of cell surface molecules act to mediate cell-cell adhesion
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The vertebrate body is mostly extracellular space. Connective tissues fill this space and are largely comprised of ECM. Amount of ECM varies: Plenty in cartilage and bone; Scarce in brain and spinal cord Connective tissue and the role of the extracellular matrix. Determines form and shape; integrates form and function. Mechanical support Substrate for cell adhesion and migration Controls cell signaling and cell differentiation. Functions of ECM
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Macromolecular Organization of ECM Macromolecular Organization of ECM
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The ECM is secreted by the cells that reside within it. Fibroblasts responsible for ECM secretion. Fibroblasts differentiate into specialized cells that secrete bone and cartilage. Epithelial cells secrete the basal lamina. Fibroblast embedded in ECM fibers
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What is the ECM? What is the ECM? Dynamic network of extracellular proteins and polysaccharides . Composition and organization varies depending on tissue. Components: Fibrous structural proteins -collagens (provide tensile strength) -elastin (provides elastic stretch) Glycosaminoglycans and proteoglycans -hydraulic properties that resist compression Adhesive proteins that allow cells to bind ECM -fibronectin -laminin
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Srtucture of collagen molecule A: Single alpha-helical chain B: Three alpha-helical chains A long, stiff, triple helical structure Three collagen alpha chains wind around to form a rope-like superhelix Rich in Proline and Glycine- Both are Important in helix formation
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Collagen fibrils provide the matrix with great tensile strength. Most abundant vertebrate protein-25%
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CBNS 101 lecture12 - The Extracellular Matrix Tissues in...

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