Question

Threshold potential is a state of depolarisation at which _____.

• A. An action potential is sure to fire
• B. Voltage gated Na+ channels open
• C. Membrane potential is near -55mV
• D. All of the above

Answer 1

The correct option is D

All of the above

Threshold potential can be defined as the state of depolarisation at which an action potential is sure to fire. When a neuronal membrane depolarizes to about -55mV, the voltage gated Na⁺ channels open. Once these channels open there is no preventing an action potential because these channels, regulated by voltage open causing a positive cascade i.e. opening of these channels depolarises the membrane further by allowing Na⁺ ions inside the cell and more depolarisation opens more voltage gated sodium channels.