Table of Contents
What happens to Na and K during action potential?
Na+ channels open at the beginning of the action potential, and Na+ moves into the axon, causing depolarization. Repolarization occurs when the K+ channels open and K+ moves out of the axon, creating a change in polarity between the outside of the cell and the inside.
What does the graph of an action potential show?
Graphing an Action Potential Scientists graph the membrane potential over time to look at how the cell is changing. This is depolarization during an action potential. At the peak, the sodium channels slam shut and the cell is no longer depolarizing.
Where are the concentrations of Na+ and K+ ions normally the greatest?
Intracellular The sodium and chloride ion concentrations are lower inside the cell than outside, and the potassium concentration is greater inside the cell.
How does K+ affect action potential?
As the K+ moves out of the cell, the membrane potential becomes more negative and starts to approach the resting potential. Typically, repolarisation overshoots the resting membrane potential, making the membrane potential more negative. This is known as hyperpolarisation.
What happens to sodium and potassium ions during depolarization?
During the depolarization phase, the gated sodium ion channels on the neuron’s membrane suddenly open and allow sodium ions (Na+) present outside the membrane to rush into the cell. With repolarization, the potassium channels open to allow the potassium ions (K+) to move out of the membrane (efflux).
Why is there hyperpolarization in action potential?
Depolarization and hyperpolarization occur when ion channels in the membrane open or close, altering the ability of particular types of ions to enter or exit the cell. The opening of channels that let positive ions flow out of the cell (or negative ions flow in) can cause hyperpolarization.
Where is there a higher concentration of sodium?
Overall, there are more positive charges on the outside of the membrane than on the inside. The concentration of sodium ions is lower inside the cell than in the extracellular fluid, while the reverse is true for potassium ions.
Which direction are the sodium and potassium being pumped?
The sodium–potassium pump is found in many cell (plasma) membranes. Powered by ATP, the pump moves sodium and potassium ions in opposite directions, each against its concentration gradient. In a single cycle of the pump, three sodium ions are extruded from and two potassium ions are imported into the cell.
What happens during repolarization of an action potential?
Repolarization is a stage of an action potential in which the cell experiences a decrease of voltage due to the efflux of potassium (K+) ions along its electrochemical gradient. This phase occurs after the cell reaches its highest voltage from depolarization.
What happens to sodium ions during depolarization?
During depolarization, the membrane potential rapidly shifts from negative to positive. As the sodium ions rush back into the cell, they add positive charge to the cell interior, and change the membrane potential from negative to positive.