Question

Consider a situation in a resting neuron, where the equilibrium potential for K+ ions is −70mV and the resting membrane potential is −90mV. What happens when a ligand-activated K channel receives a signal that causes the channel to open?

a.K+ ions move into the cell in response to the electrochemical gradient, causing a slight depolarization.
b.K+ ions move into the cell in response to the electrochemical gradient, causing a slight hyperpolarization.
c.K+ ions move out of the cell in response to the electrochemical gradient, causing a slight hyperpolarization.
d.K+ ions move out of the cell in response to the electrochemical gradient, causing a slight depolarization.

Answer 1

When a ligand-activated K+ channel opens in a resting neuron, K+ ions move out of the cell, leading to a slight hyperpolarization, further increasing the negativity of the membrane potential.

Step-by-step explanation:

When a ligand-activated K+ channel in a resting neuron receives a signal that causes it to open, K+ ions will move in response to the electrochemical gradient. Since the equilibrium potential for K+ is -70mV and the resting membrane potential is -90mV, K+ ions will move out of the cell towards the equilibrium potential. This movement out of the cell will cause a slight hyperpolarization, increasing the negatively charged difference across the cell membrane (more negative than the resting membrane potential). Therefore, the correct answer is: c. K+ ions move out of the cell in response to the electrochemical gradient, causing a slight hyperpolarization.