An action potential in a nerve fibre A. Occurs when its membrane pote

1.	An action potential in a nerve fibre A. Occurs when its membrane potential is hyperpolarized to a critical level. B. Is associated with a transient increase in membrane permeability to sodium. C. Is associated with a transient decrease in membrane permeability to potassium. D. Induces local electrical currents in adjacent segments of the fibre. E. Has an amplitude which varies directly with the strength of stimulus.
Answer» A. False It occurs when the membrane potential is reduced to its threshold for firing. B. True This leads to rapid depolarization towards the sodium equilibrium potential. C. False Permeability to K⁺ increases and the resulting K⁺ efflux contributes to membrane repolarization. D. True This depolarizes the adjacent axon and leads to propagation of the impulse. E. False Because of the ‘all or none’ law, impulse configuration is independent of stimulus strength.

An action potential in a nerve fibre A. Occurs when its membrane potential is hyperpolarized to a critical level. B. Is associated with a transient increase in membrane permeability to sodium. C. Is associated with a transient decrease in membrane permeability to potassium. D. Induces local electrical currents in adjacent segments of the fibre. E. Has an amplitude which varies directly with the strength of stimulus.

Answer»

A. False It occurs when the membrane potential is reduced to its threshold for firing.

B. True This leads to rapid depolarization towards the sodium equilibrium potential.

C. False Permeability to K⁺ increases and the resulting K⁺ efflux contributes to membrane repolarization.

D. True This depolarizes the adjacent axon and leads to propagation of the impulse.

E. False Because of the ‘all or none’ law, impulse configuration is independent of stimulus strength.

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