Question

Which of the following situations in a neuron results in action potentials that have extended depolarization phases?

A. Inhibiting the voltage-gated Na⁺ channels.
B. Stimulating the voltage-gated K⁺ channels.
C. Compromising the inactivation mechanism in voltage-gated Na+ channels.
D. Compromising the inactivation mechanism in voltage-gated K+ channels.
E. None of the above.

Answer 1

Extended depolarization phases in action potentials are caused by a C. compromised inactivation mechanism in voltage-gated Na+ channels, where these channels do not close properly, leading to prolonged Na+ influx.

Step-by-step explanation:

The situation in a neuron that results in action potentials with extended depolarization phases is C. Compromising the inactivation mechanism in voltage-gated Na+ channels.

Normally, during an action potential, these Na+ channels inactivate shortly after opening, which prevents further Na+ from entering the cell and allows repolarization to occur.

When the inactivation mechanism is compromised, the Na+ channels do not close properly during this time, leading to a prolonged period of depolarization as Na+ continues to enter the cell.