1. The concentration of Na+ is higher outside of a cell, and the cell has a memb
ID: 204205 • Letter: 1
Question
1. The concentration of Na+ is higher outside of a cell, and the cell has a membrane potential of
-10 mV. Based on the chemical and electrical gradients, in what direction is the net movement of Na+?
2.. During the course of an action potential, the membrane potential rapidly rises and reaches a peak of about +40 mV before falling to about -75 mV. What causes the fall in membrane potential?
-A decrease in the permeability to both Na+ and K+
-A decrease in Na+ permeability, and an increase in K+ permeability
1. The concentration of Na+ is higher outside of a cell, and the cell has a membrane potential of
-10 mV. Based on the chemical and electrical gradients, in what direction is the net movement of Na+?
-Out of the cell -The chemical and electrical gradients oppose each other; therefore, it is impossible to determine the net movement of Na+ -Into the cell -The chemical and electrical gradients oppose each other, so there is no net movement of Na+2.. During the course of an action potential, the membrane potential rapidly rises and reaches a peak of about +40 mV before falling to about -75 mV. What causes the fall in membrane potential?
-A decrease in the permeability to both Na+ and K+
Explanation / Answer
1. Into the cell. Movement of ions is based on chemical gradient.
2. Fall in membrane potential (repolarisation) is due to a decrease in Na + permeability and an increase K+ permeability.
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