General & Nerve-Muscle Physiology · NEET PG Preparation Physiology
Which of the following describes the molecular mechanism responsible for the absolute refractory period of a nerve action potential?
Practice question from General & Nerve-Muscle Physiology (NEET PG Preparation Physiology), with the correct answer and a step-by-step solution.
medium · MCQ · Q-4D3A59
Which of the following describes the molecular mechanism responsible for the absolute refractory period of a nerve action potential?
- A.Activation of voltage-gated potassium channels
- B.Inactivation of voltage-gated sodium channelsCorrect answer
- C.Hyperpolarization due to sustained potassium efflux
- D.Depletion of intracellular ATP
Solution
The absolute refractory period is caused by the closure of the inactivation gates (h-gates) of voltage-gated sodium channels. Until the membrane repolarizes and these channels return to their resting (closed but capable of opening) state, a second action potential cannot be generated regardless of the stimulus strength.
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