Question

which of the following will occur when an excitatory postsynaptic potential (epsp) being generated on the dendritic membrane? a) a single type of channel will open, permitting simultaneous flow of sodium and potassium. b) specific potassium gates will open. c) sodium gates will open first, then close as potassium gates open. d) specific sodium gates will open.

Explanation:

When an excitatory postsynaptic potential (EPSP) is generated on the dendritic membrane, a single type of channel (ligand - gated ion channel) opens. This channel allows the simultaneous flow of sodium (\(Na^+\)) and potassium (\(K^+\)) ions. Sodium has a stronger electrochemical gradient driving it into the cell compared to the potassium gradient driving it out. So, there is a net influx of positive charge (depolarization). Option B is incorrect as it only mentions potassium. Option C is incorrect as it implies a sequential opening of sodium and then potassium gates which is not the case for EPSP - generating channels. Option D is incorrect as it is not specific sodium gates (like voltage - gated sodium channels for action potentials) but a different type of channel (ligand - gated) that allows both \(Na^+\) and \(K^+\) flow.

Answer:

A. A single type of channel will open, permitting simultaneous flow of sodium and potassium.