Lab7_OCON_NGUY_BOUL_POLL - Caroline OConnor, Melissa...

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Caroline O’Connor, Melissa Pollesch, John Nguyen, Michelle Boulanger Lab 7: Membrane Transport T.A. James Peterman 1.) A. Ringer’s/Ringers: Ions are flowing normally without counter current, and the ion flux represents Na+ flux when counter current is applied. B. Cl-free/Cl-free: Application of a counter current will inhibit passive diffusion of Cl- ions through the tight junctions; however, ion flux still is only represented by Na+ flux; therefore, we predict that there will be no difference in amperage and no change in ion flux between the control conditions in A and the experimental conditions in B. C. Ringer’s/Ringers: same as control above D. Na+ free Ringer’s/Na+ free Ringers: Because of the absence of Na+ ions, we predict that there will be no change in amperage, thus no electrical potential, and no ion flux. E. Na+ free Ringer’s/Ringer’s: ATPase Na+/K+ pump is still functionally pumping 3 Na+ ions out and 2 K+ ions in; however, because there is no Na+ present on the mucosal side, we predict that there will eventually be little to no electrical potential, and no ion flux. F. Ringer’s/Ringer’s: same as controls above G. 20% Ringer’s/Ringer’s: Because of the low driving force of Na+ to passively diffuse into the cell due to a low concentration gradient, we predict that electrical potential will be lower than the control and that ion flux will significantly decrease. H. 60% Ringer’s/Ringer’s: At around a 60% concentration of Ringer’s, the Na+ channels will begin to become saturated: therefore, we predict that the rate of ion flux will eventually plateau, and little change will be observed in electrical potential or ion flux. I, J. 100% and 120% Ringer’s/Ringers: we predict that, because of the same saturation concept in H, there will be no change in electrical potential or ion flux. K. Ringer’s/ouabain (over 10 min): Ouabain works to destroy the ATPase Na+/K+ pump. Therefore, Na+ will only be passively diffusing through the mucosal side of the membrane. However, passive diffusion will eventually reach equilibrium. We predict that, over time, electrical potential will decrease until it reaches a plateau, and that ion flux will decrease until in reaches 0. 2.)
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Test 1 and 2 The electrical potential represents the amount of Na+ that is being pumped across the frog skin from the outside in, (mucosal to serosal side) In addition the gradient created from the Na+ pumping brings with Cl- ions as well. The movement of the Na+ and Cl- ions creates an electrical current, which is the
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This note was uploaded on 08/11/2010 for the course IPHY 3060 taught by Professor Allen,davi during the Fall '09 term at Colorado.

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Lab7_OCON_NGUY_BOUL_POLL - Caroline OConnor, Melissa...

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