Tonicity how a cell a tonicity reacts in a solution

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Unformatted text preview: ute/kg water 5. Comparing two solutions a) Isosmotic (same) b) Hyperosmotic (more) c) Hyposmotic (less) Figure 5-26: Osmosis and osmotic pressure 14 1/31/2010 A. Tonicity: How a Cell A. Tonicity Reacts in a Solution Reacts • Depends on Depends osmolarity, but also osmolarity but permeability of permeability of solutes solutes – = measure of the measure effect on the cell !!! effect • Penetrating solute • Non-penetrating solute ******************** 1) Isotonic cell same 2) Hypertonic cell shrivels 28a, 3) Hypotonic cell swells Figure 5-28a, b: Tonicity depends on the relative concentrations of nonpenetrating solutes nonpenetrating Tonicity: How a Cell Tonicity: Reacts in a Solution Reacts • Penetrating solutes Penetrating can move and disrupt the chemical / osmotic equilibrium!! osmotic Figure 5-28c, d: Tonicity depends 28c, on the relative concentrations of nonpenetrating solutes nonpenetrating 15 1/31/2010 B. Electrical Disequilibrium • Separation of charged ions – Membrane insulates – Potential = stored energy; required to keep charges separate Potential stored – Conduction of signal – when broken locally Conduction • Electrochemical gradient Figure 5-29: Separation of electrical charge 29: C. Membrane Potentials: Change with Permeability Change 1. Resting 2. Equilibrium Equilibrium 3. Channel opening 3. a) Voltage gated Voltage b) ATP gated (leak) b) ATP 16...
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This document was uploaded on 03/18/2010.

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