Question

A neuron has a resting potential of -75mV and a threshold of -55mV. Which of the scenarios below would make this neuron more excitable?

a. the contribution of 6 excitatory local potentials instead of 3
b. decreasing extracellular potassium so there's more room for sodium to come in
c. increasing extracellular sodium for a higher action potential spike height
d. A and B c. A, B and C

Answer 1

To make a neuron more excitable and likely to reach the threshold potential for an action potential, increasing excitatory local potentials and decreasing extracellular potassium are effective. Increasing extracellular sodium primarily affects the spike height of an action potential, not excitability.

Step-by-step explanation:

The question is asking which scenarios would make a neuron more excitable. A neuron's excitability is related to how easily it can reach the threshold potential and initiate an action potential. The resting potential of a neuron is around -70 mV, but this particular neuron has a resting potential of -75 mV and a threshold of -55 mV.

• Increasing excitatory local potentials contributes to the depolarization of the neuron, which makes it more likely to reach the threshold potential and fire an action potential.
• Decreasing extracellular potassium affects the membrane potential by increasing the driving force for sodium to enter the neuron, making it more likely to reach the threshold.
• Increasing extracellular sodium would affect the height of the action potential spike but does not directly make the neuron more excitable in terms of reaching the threshold.

Therefore, the scenarios that would make the neuron more excitable are increasing excitatory local potentials and decreasing extracellular potassium, making option d (A and B) correct.