Question

You are measuring the resting membrane potentials (RMP) and the threshold to fire an action potential in neurons from two different animals. The cat neuron has a RMP of -70mV and a threshold of -50mV. The frog neuron has a RMP of -80mV and a threshold of -60mV. Which one of these neurons is more excitable and why?

1) the cat neuron is more excitable because it has a higher RMP
2) the cat neuron is more excitable because it has a higher threshold
3) the frog neuron is more excitable because it has a lower threshold
4) the frog neuron is more excitable because it has lower RMP
5) the neurons are equally excitable because there is an equal voltage between their RMPs and thresholds

Answer 1

The frog neuron is more excitable because it has a lower threshold.

Step-by-step explanation:

The frog neuron is more excitable because it has a lower threshold.

The resting membrane potential (RMP) is the voltage difference across the cell membrane when the neuron is not sending signals. The RMP of the cat neuron is -70mV, while the RMP of the frog neuron is -80mV. The threshold is the membrane potential at which an action potential is initiated. The threshold of the cat neuron is -50mV, while the threshold of the frog neuron is -60mV.

A lower threshold means that the neuron is more easily triggered to fire an action potential. Since the threshold of the frog neuron is lower than that of the cat neuron, the frog neuron is more excitable.