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Unformatted text preview: Problem set 1 – Resting membrane potential KEY 01/13/2012 1. a. The sum of charges from inorganic cations (Na + , K + , Ca 2+ and Mg 2+ ) in the intracellular medium is: The inorganic anion charge (Cl – ) is: Therefore, since the electroneutrality of the intracellular solution must be maintained, that is, the total positive charge must equal the negative charge, there must be impermeant anions in addition to the permeant Cl – shown in the table. b. Since the animal is poikilothermic, body temperature T = 20 °C = 293 K. The equilibrium potential for Na + is: The equilibrium potential for K + is: The equilibrium potential for Ca 2+ is: The equilibrium potential for Mg 2+ is: (Of course, since there is no concentration gradient for Mg 2+ , the equilibrium occurs when there is also no electrical gradient, i.e., ). The equilibrium potential for Cl – is: c. Since the membrane is permeable to Na + , K + , Ca 2+ , Mg 2+ and Cl – , the membrane potential () will fall somewhere in between the equilibrium potentials for those ions. Considering the most negative equilibrium potential among the permeable ions is , the most negative...
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This note was uploaded on 02/02/2012 for the course BIOLOGY 222 taught by Professor Nagaya during the Winter '11 term at University of Michigan.
- Winter '11