General & Nerve-Muscle Physiology · NEET PG Preparation Physiology
A 24-year-old medical student is studying action potential generation in the giant axon of a squid. While recording the membrane potential, a specifi…
Practice question from General & Nerve-Muscle Physiology (NEET PG Preparation Physiology), with the correct answer and a step-by-step solution.
medium · MCQ · Q-CE60D3
A 24-year-old medical student is studying action potential generation in the giant axon of a squid. While recording the membrane potential, a specific neurotoxin is applied that completely abolishes the early inward current without affecting the delayed outward current. Which of the following channels was most likely blocked?
- A.Voltage-gated sodium channelsCorrect answer
- B.Voltage-gated potassium channels
- C.Inward rectifier potassium channels
- D.L-type calcium channels
Solution
The early inward current during an action potential is carried by the rapid influx of sodium ions through voltage-gated sodium channels. Tetrodotoxin (TTX) is a classic blocker of these channels. The delayed outward current is carried by potassium ions flowing through voltage-gated potassium channels (blocked by TEA).
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