NEET PG DENTAL EXAM

Detailed explanation-1: -Voltage-gated sodium channels at the part of the axon closest to the cell body activate, thanks to the recently depolarized cell body. This lets positively charged sodium ions flow into the negatively charged axon, and depolarize the surrounding axon.

Detailed explanation-2: -The depolarization, also called the rising phase, is caused when positively charged sodium ions (Na+) suddenly rush through open voltage-gated sodium channels into a neuron. As additional sodium rushes in, the membrane potential actually reverses its polarity.

Detailed explanation-3: -Because there are many more sodium ions on the outside, and the inside of the neuron is negative relative to the outside, sodium ions rush into the neuron. Remember, sodium has a positive charge, so the neuron becomes more positive and becomes depolarized.

Detailed explanation-4: -The diffusion of potassium ions out of a neuron causes regain of resting potential. The resting membrane potential is restored due to action of voltage gated (K+) channels which open due to membrane depolarisation and cause efflux of (K+) ions out of the neuron. It continues till the resting potential becomes-70 mV.