Chapter 43, Problem 1U

Which of the following best describes the electrical state of a neuron at rest?

a. The inside of a neuron is more negatively charged than the outside.

b. The outside of a neuron is more negatively charged than the inside.

c. The inside and the outside of a neuron have the same electrical charge.

d. Potassium ions leak into a neuron at rest.

Summary Introduction

Introduction:

The electric potential is generated across the membrane by the neurons. The efficient functioning of the neurons is based on the generation of electric potential because it modifies the propagation of the signals across the cells.

Answer to Problem 1U

Correct answer:

The negative potential is maintained inside the neuron as compared to that of the outside when the neuron is at resting position. The difference between the potential between the inside and outside of a neuron is called the resting potential. Therefore, option a. is correct.

Explanation of Solution

Reason for the correct statement:

The negative potential of the inside of the cell is maintained due to the difference of the concentration of ions, such that the inside of the cell has a high level of potassium and low level of sodium. The outside of the cell has a high level of sodium and low level of potassium.

Option a. is given as “The inside of a neuron is more negatively charged than the outside”.

As, “potassium is present in high levels inside the cell, thus the inside of the cell has more negative potential that outside”, is the right answer.

Hence, option a. is correct.

Reasons for the incorrect statements:

Option b. is given as “The outside of a neuron is more negatively charged than the inside”.

The outside region of the cell is more positively charged than the inside of the cell. So, it is a wrong answer.

Option c. is given as “The inside and the outside of a neuron have the same electrical charge”.

Due to the difference between the concentrations of the ions inside and outside of neuron, they both cannot have same electrical charge. So, it is a wrong answer.

Option d. is given as “Potassium ions leak into a neuron at rest”.

There are more potassium ions inside the neuron than that of the outside of the neuron. The potassium ions will leak outside of the neuron. So, it is a wrong answer.

Hence, options b., c., and d. are incorrect.

Conclusion

The resting state of a neuron is defined as the state when the inside of the neuron is more negatively charged than the outside region of the neuron.