Question

Typical value of resting membrane potential of a neuron is
(A) + 40 mv
(B) - 60 mv
(C) - 70 mv
(D) + 80 mv

Answer 1

Hint: The concept of the resting membrane potential of any cell can easily be well understood by imagining it in the form of equilibrium potential. Different types of cells have different values of their resting potential which ranges from −8 mV for chondrocytes to −95 mV for skeletal muscle cells.

Complete answer:
Neurons are considered as excitable cells as their membranes remain in a polarised state because of the difference in their concentration gradient of ions across the membrane. The potential difference which is nothing but a charge generated across the cell membrane of neuron or nerve cells is negative inside the cell with respect to the outside of the cell. In this condition, the membrane is said to be polarised.

When the potential difference across the cell membrane is at rest, it is known as Resting Potential. The resting potential of neurons is about −70 mV which usually ranges between −60 mV to −85 mV. This resting potential is maintained by active transport as well as passive diffusion of ions.

The active transport plays an important role in the maintenance of resting potential because of the transport of ions against the electrochemical gradient by Sodium potassium pump. These pumps are known to be carrier proteins that are located in the cell membrane and require ATP to remove three sodium ions from the axon coupled with the uptake of two potassium ions. The passive diffusion of ions competes with the active movement. The ion permeability of the axon membrane defines the diffusion rate in the case of Passive transport.

Hence, the correct answer is option (C).

Note: The loss of potassium ions from the axon is greater than that of sodium ions because the membrane permeability of potassium ions is greater than sodium ions. This creates a net loss of positive ions from axons while a negative charge is produced within the axon.