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Q.
A polarized neuron is said to be in
NTA AbhyasNTA Abhyas 2020
Solution:
On the membrane of the neuron, different types of ion channels are present. These channels are selectively permeable to a variety of ions. The membrane of the axon becomes more permeable to potassium ions (K+) and almost impermeable to sodium ions (Na+) when the neuron is not conducting any impulse. This makes the membrane impermeable to negatively charged proteins present in the axoplasm.
The axoplasm is packed with a high concentration of potassium ions (K+) and negatively charged proteins and low concentration of sodium ions (Na+). On the other hand, the fluid outside the axon contains low concentration of potassium ions (K+) and high concentration of sodium ions (Na+), thus forming a concentration gradient.
This ionic gradient is maintained by the sodium-potassium pump which transports 3 Na+ for every 2 K+ into the cell membrane. This results in the possession of a positive charge on the axonal membrane and the development of a negative charge on the inside of the membrane, thus making it polarised.
This imbalance of electrical charge that is present between the inner and the outer surface of the membrane, thus creating a potential difference in a resting membrane is called as resting potential.