Multiple Choice
K+ leak channels are important for doing what?
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9. Transport Across Membranes
Ion Channels and Membrane Potential
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Which of the following is true regarding the opening of a sodium ion channel?
A
It is primarily responsible for maintaining the resting membrane potential.
B
It results in the movement of sodium ions out of the cell.
C
It causes the membrane potential to become more positive (depolarization).
D
It leads to hyperpolarization of the membrane.
Verified step by step guidance1
Understand the role of sodium ion channels: Sodium ion channels are membrane proteins that allow sodium ions (Na⁺) to move across the cell membrane when they open. This movement is driven by the electrochemical gradient of sodium ions.
Recall the resting membrane potential: At rest, the inside of the cell is more negative compared to the outside, typically around -70 mV. Sodium ions are more concentrated outside the cell than inside, creating a gradient.
Analyze what happens when sodium ion channels open: When these channels open, sodium ions move into the cell due to the concentration gradient and the negative charge inside the cell, which attracts the positively charged sodium ions.
Determine the effect on membrane potential: The influx of positively charged sodium ions makes the inside of the cell less negative (more positive), a process known as depolarization.
Conclude the correct statement: The opening of sodium ion channels causes the membrane potential to become more positive, leading to depolarization. This is the correct answer to the problem.
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