Question

1. How would each of the following manipulations affect the shape of an action potential?
   1. Reduced concentration of K⁺ inside the cell.
   2. Blockade of voltage-gated Na⁺ channels.
2. Which of the following changes during an action potential?
   1. V_m
   2. E_Na
   3. V_m and E_Na
   4. Neither V_m nor E_Na

Answer 1

1 Ans: K+ ions are usually present in higher concentrations inside the cell and Na+ ions are found at higher concentrations outside the cell. So, K+ ions tend to move outside the cell and Na+ ions tend to move inside the cell down their concentration gradient.

a. If K+ ion concentration decreases inside the cell, it signifies an increase in K+ ion concentration outside the cell. The potassium gradient in such cells will decrease and the resting membrane potential becomes more positive.

b. Voltage-gated Na+ channel assists cells in depolarization as it allows the movement of Na+ ions to move inside the cell down their electrochemical gradient due to a change in potential. If these channels were blocked, Cells will fail to depolarize and generate an action potential.