How do graded changes in membrane potential give rise to all-or-none changes that generate action potentials?
A) The membrane recognizes only action potentials generated by positive ions,causing a voltage threshold to be reached.
B) The membrane recognizes only action potentials generated by negative ions,causing a voltage threshold to be reached.
C) Many graded potentials at different points along the membrane are summed,causing the voltage threshold to be reached.
D) Many graded potentials reaching the same point on the membrane are summed,causing the voltage threshold to be reached.
E) The membrane allows only voltage-gated channels to open and close,enabling an electrical charge gradient to be created.

Question

Quizplus · Accepted Answer

Graded potentials at different points on the membrane must summate (add up) to produce a depolarization that reaches the threshold voltage in order to generate an action potential. This is called spatial summation. If multiple graded potentials arrive at the same point on the membrane, they must summate temporally (in time) to generate a depolarization that reaches the threshold voltage, which is called temporal summation. Only when this threshold is reached will voltage-gated channels open and an action potential will be generated. Therefore, changes in the membrane potential (graded potentials) must be integrated and summated in order to produce an all-or-none response (action potential).

How Do Graded Changes in Membrane Potential Give Rise to All-Or-None