EVERYDAY SCIENCE

Detailed explanation-1: -Voltage-gated sodium channels open once the cell’s membrane potential reaches threshold. The rapid influx of sodium results in a large depolarization called the rising phase.

Detailed explanation-2: -An action potential is a transient, electrical signal, which is caused by a rapid change in resting membrane potential (-70 mV). This occurs when the threshold potential (-55 mV) is reached, this causes a rapid opening in the voltage-gated sodium channels leading to an influx of sodium ions into the cell.

Detailed explanation-3: -If the threshold of excitation is reached, all Na+ channels open and the membrane depolarizes. At the peak action potential, K+ channels open and K+ begins to leave the cell. At the same time, Na+ channels close. The membrane becomes hyperpolarized as K+ ions continue to leave the cell.

Detailed explanation-4: -Voltage-gated sodium channels play an important role in action potentials. If enough channels open when there is a change in the cell’s membrane potential, a small but significant number of Na+ ions will move into the cell down their electrochemical gradient, further depolarizing the cell.

Detailed explanation-5: -When depolarization reaches threshold potential level, its regenerative circulation mechanism opens a great quantity of Na+ channels through positive feedback. There is potential difference between the excited area and adjacent unexcited areas, so local current occurs.