A nerve impulse is caused by
A)the movement of a sodium ion all the way from dendrite to axon tip.
B)the movement of a potassium ion all the way from dendrite to axon tip.
C)the movement of an electron all the way from dendrite to axon tip.
D)a change in the difference in positive and negative ions on the outer and inner surfaces of the neuron membrane,a change that opens adjacent channels and propagates its flow.
E)a change in the difference in sugar molecules on the outer and inner surfaces of the neuron membrane that opens adjacent channels.

Question

Quizplus · Accepted Answer

A nerve impulse, also known as action potential, is caused by a change in the electrochemical gradient across the neuron membrane. This change occurs due to the movement of positively charged ions, particularly sodium (Na+) and potassium (K+), across the membrane via ion channels. When a neuron is at rest, the inside of the cell is negatively charged compared to the outside, with a concentration of K+ ions inside and Na+ ions outside. However, when a stimulus reaches the neuron, ion channels open that allow Na+ to rush into the cell, creating a positive charge inside the cell. This change in voltage opens adjacent ion channels, propagating the flow of the impulse down the axon. Therefore, choice D is the correct answer. Choices A, B, and E are incorrect because they describe the movement of a single type of ion or a non-ion substance, and do not accurately reflect the complex interactions of multiple ions necessary to create a nerve impulse.

A Nerve Impulse Is Caused by