161k views
4 votes
Which of the following statements is FALSE regarding Na+ and K+ in a two-voltage dependent membrane conductance?

A. Na+ conductance increases with increased membrane potential and its chances of moving in also increase
B. K+ conductance increases with increased membrane potential and its chances of moving out will increase
C. K+ conductance is a short peak and Na+ is a long peak
D. Early influx of Na+ into the neuron produces a transient inward current
E. Na+ and K+ conductance change overtime and are voltage dependent

User Alex Chase
by
7.5k points

1 Answer

4 votes

Final answer:

The false statement is that K+ conductance increases and its chances of moving out will increase; in fact, K+ conductance does increase, but K+ moves out of the cell, repolarizing the membrane.

Step-by-step explanation:

The false statement regarding Na+ and K+ in a two-voltage dependent membrane conductance is: "K+ conductance increases with increased membrane potential and its chances of moving out will increase". While K+ conductance does increase with an increased membrane potential, K+ moves out of the cell rather than in. This outward movement repolarizes the membrane. In contrast, Na+ conductance indeed increases with increased membrane potential and Na+ moves into the neuron, causing depolarization.

The sequence of ion movement during an action potential begins with the influx of Na+ ions into the neuron, which produces a transient inward current. This causes the membrane potential to rise and depolarize. Subsequently, voltage-gated K+ channels open, but with a delay compared to Na+ channels. K+ begins to leave the cell, aiding the membrane in returning to its resting potential through repolarization followed by hyperpolarizing overshoot as a result of slightly delayed closure of K+ channels.

User Mrdenny
by
8.6k points