Question

Which of the following will open a sodium voltage gated channel in the axon hillock?

A stimulus that reduces the number of Na+ in the intracellular fluid

A stimulus that makes the intracellular fluid more negative

Hyperpolarizing stimulus

Depolarizing stimulus

Answer 1

D. Depolarizing stimulus

• When depolarizing stimulus reach axon hillock then all the mlvoltage gated sodium channel open up. This causes influx of sodium (sodium concentration increases inside). This also makes intracellular fluid more positive.
• Therefore a depolarizing stimulus or stimulus which makes intracellular fluid more positive or stimulus that increases the number of Na+ in intracellular fluid will open voltage gated ion channel.
• Hyperpolarizing stimulus does opposite (makes it difficult for voltage gated ion channel to open).