Question

multiple choice question
an excitatory postsynaptic potential (epsp) occurs when neurotransmitters bind to their receptors and open chemically - gated ______ channels.
potassium
calcium
magnesium
sodium

Explanation:

An excitatory postsynaptic potential (EPSP) is a graded potential that makes the postsynaptic neuron more likely to fire an action potential. When neurotransmitters bind to their receptors on the postsynaptic membrane, they open chemically - gated ion channels. Sodium (\(Na^+\)) has a higher concentration outside the neuron. When sodium channels open, \(Na^+\) flows into the neuron, depolarizing it (making the inside of the neuron more positive). This depolarization is what constitutes an EPSP. Potassium (\(K^+\)) outflow (if channels were to open in a way that causes more outflow) would hyperpolarize the neuron (make it more negative inside), which is an inhibitory effect. Calcium (\(Ca^{2 +}\)) channels are important in other processes like neurotransmitter release from the presynaptic neuron but not the main ion for EPSP generation at the postsynaptic membrane in most common cases. Magnesium (\(Mg^{2+}\)) is not the ion associated with the generation of EPSP.

Answer:

sodium