Chapter 6

Chapter 6 - 8.17.11 Chapter 6 Interactions Between Cells...

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8.17.11 (slide 4) -membrane physiology The Cell (slide 6) -cross section -**know organelles and basic functions -nucleus houses genetic material -small vesicles -cell membrane (pink): barrier between what is a cell and what isn’t a cell (slide 7) -Cell -cytoplasm -includes everything inside: aqueous environment and organelles - cytosol -organelles -nucleus -set apart from organelles because the membrane is porous and double layer -cell (plasma) membrane -Extracellular space -Pink “lipid bi-layer” -made of phospholipids -polar heads -tails are hydrophobic -Blue “proteins” -“red” complex carbohydrates attached The Extracellular Environment (slide 9) -The cell membrane acts as a physical barrier between the cytoplasm (inside of the cell) and the extracellular fluid (ECF, outside of the cell) -living organisms are about 2/3 water by weight (~70%) -Total body water is divided -Intracellular compartments (2/3, ~67%) -Extracellular compartments (1/3, ~33%) -20% as vascular fluid (blood plasma) -80% as interstitial fluid (non-vascular “tissue fluid” within extracellular matrix -between tissues, but not vascular Extracellular & Intracellular Compartments (slide 10) -Figure 14.8 The Extracellular Environment (slide 11) -Extracellular environment includes everything outside of cells -ECM (extracellular matrix) -gel-like hydrated material -“ground substance” -glycoproteins (Integrins) -proteoglycans -protein fibers -collagen
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-elastin -Extracellular space more viscous and jelly like **Selective Permeability of Cell Membranes (slide 12) -Phospholipid bilayer -polar heads -hydrophobic tails -very few substances can pass through phospholipid bilayer most biological substances cannot just diffuse through phsopholipid bilayer -most are polar, small, ions with charges -use carrier-mediated transport (proteins will help molecules move in and out) -large uncharged polar molecules -ions -charged polar molecules -Cells are dynamic, cell membranes can change -depending on environment and conditions Solutions & Diffusion (slide 14) -biological systems are water-based -aqueous solutions -water is solvent -other substances are solute -concentration: amount of solute relative to the amount of solution (or solvent) -concentration differences (gradients) lead to the “downhill” net diffusion of solute from high to low concentration -concentration difference across barrier causes movement -net diffusion stops when equilibrium is reached -when concentration is equal -uncharged solutes (glucose, sucrose) -dynamic equilibrium: equal concentrations but still small amount of movement Simple Diffusion Across a Cell Membrane (slide 15) -the diffusional driving force is proportional to the strength of the concentration gradient -the larger the difference of concentration, the stronger the driving force -degree to which (whether) a substance will diffuse across a lipid bilayer is dependent on the selective permeability of that membrane
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This note was uploaded on 10/04/2011 for the course VPHY 3100 taught by Professor W during the Fall '05 term at UGA.

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Chapter 6 - 8.17.11 Chapter 6 Interactions Between Cells...

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