Question

The following are the main steps in the generation of an action potential:

1. sodium channels are inactivated
2. more voltage-regulated potassium channels open and potassium moves out of the cell, initiating repolarization
3. sodium channels regain their normal properties
4. a graded depolarization brings an area of an excitable membrane to threshold
5. a temporary hyperpolarization occurs
6. sodium channel activation occurs
7. sodium ions enter the cell and further depolarization occurs

The proper sequence of these events is

A. 4, 6, 7, 3, 2, 5, 1.

B. 4, 6, 7, 1, 2, 5, 3.

C. 6, 7, 4, 1, 2, 3, 5.

D. 2, 4, 6, 7, 1, 3, 5.

E. 4, 2, 5, 6, 7, 3, 1.

Answer 1

The correct sequence for the steps of an action potential is 4, 6, 7, 1, 2, 5, 3, beginning with a graded depolarization and ending with the recovery of the sodium channels to their normal properties after a temporary hyperpolarization.

Step-by-step explanation:

The generation of an action potential follows a specific sequence involving the depolarization and repolarization of a neuron's membrane. First, a graded depolarization brings an area of an excitable membrane to threshold (4), then sodium channel activation occurs (6), allowing sodium ions to enter the cell and further depolarization happens (7). Subsequently, sodium channels are inactivated (1), leading to more voltage-regulated potassium channels opening and potassium moving out of the cell, initiating repolarization (2). A temporary hyperpolarization occurs (5), before the sodium channels regain their normal properties (3).