Lecture10_103431

Lecture10_103431 - Click to edit Master subtitle style Cell...

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Unformatted text preview: Click to edit Master subtitle style Cell Signaling and Membrane Potential October 14, 2010 Cell Membrane Forms cell boundary Encloses intracellular contents Separates them from extracellular environment Cell Membrane Determines composition of cell Entry of nutrients Exit of wastes Exit of secretory products Maintain differences in ion concentrations Joins cells together Allows the cell to respond to environmental signals Extracellular and Intracellular Fluid Intracellular fluid Inside cells 2/3rds of total body H2O Extracellular fluid Outside of cells 1/3 of total body H2O 20% of ECF is blood plasma 80% of ECF is interstitial/tissue fluid Gel-like matrix Extracellular matrix Biological glue Intricate meshwork of fibrous proteins embedded in a watery, gel-like substance composed of complex carbohydrates Watery gel provides pathway for diffusion of nutrients, wastes, and other water-soluble traffic between the blood and tissue cells (interstitial fluid) Interwoven in this gel are three major types of protein Extracellular Matrix Protein fibers: collagen and elastin Gel-like ground subtance Interstitial fluid is part of the ground substance Contains glycoproteins = proteins with numerous sugar side chains Proteoglycans Extracellular matrix proteins Collagen : Forms cable-like fibers that assemble into sheets Provide tensile strength Elastin : Rubber-like fibers Most abundant in tissues that must be capable of stretching and recoiling (e.g. lungs) Fibronectin : Promotes cell adhesion and holds cells in position Levels are reduced in cancer Extracellular Matrix Collagen and elastin like iron bars in concrete provide structural strength Collagen IV contributes to the basal lamina/basement membrane By forming chemical bonds between carbohydrates on the outside surface of the plasma membrane of overlying cells, glycoproteins and proteoglycans of the matrix strengthen the adhesions Plasma Membrane Composition Amphipathic phospholipids = Contain both polar (water- soluble/hydrophilic) and nonpolar (water- insoluble/hydrophobic) portions Self-assemble into bilayer Cholesterol = Give the membrane stability and fluidity Membrane proteins Integral and peripheral Carbohydrates Fluid Mosaic Model Membrane Proteins: Integral Proteins Channels Leak Gated Carriers Membrane Carbohydrates Self-recognition Cell-cell interactions Tissue growth Cell-Cell and Cell-Matrix Adhesions Cell adhesion molecules (CAMs) Specialized cell junctions Extracellular matrix Glue Fibrous proteins Collagen Elastin Fibronectin Carbohydrate gel Cell-Cell Adhesions Desmosomes Adhering Tight junctions Impermeable Gap junctions Communicating Desmosomes Act like snaps that anchor together two closely adjacent but non-...
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This note was uploaded on 04/12/2011 for the course BIOL 1020 taught by Professor Staff during the Spring '11 term at North Texas.

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Lecture10_103431 - Click to edit Master subtitle style Cell...

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