Refer to the graph below The graph shows the action potentia

Refer to the graph below. The graph shows the action potential produced in the axon of a neuron before (dotted purple line) and after (solid red line) the neuron was exposed to a chemical agent. Based on the change in the action potential trace, what was the most direct effect that the chemical agent had on the neuron? The agent blocked voltage-gated potassium channels. The agent blocked voltage-gated sodium channels. The agent blocked neurotransmitter vesicle formation. The agent blocked neurotransmitter release from the neuron.

Solution

Ans b

The agent blocked voltage gated sodium channels. The resting potential of neuron is approx -55mv which is called as resting potential. Now when stimulus arrives, the sodium channels ooen, and the positive charge enters into it, causing the potential to rise upto +60mv , the process called aa depolarisation. Now potassium channels open, and K+ ions leak, causing the membrane potential to become -85mv, process called as re polarisation.

So this curve shows negative membrane potential indicating blockage of sodium channels