post-lecture chapter 8

Which membrane potential opens a sufficient number of the voltage-gated Na+Na+ channels to cause a significant change in the membrane potential (making it much less negative).

-60mV

What is the resting membrane potential of the neuron used in the experiment?

-80mV

-->Arrange the following events in the correct order, from left to right, with respect to the function of the channels, ion permeability, and changes in membrane potential. Rank the items from first to last. To rank items as equivalent, overlap them.

1. opening of voltage-gated Na+ channels 2. Na+ ion flow into the neuron increases 3. depolarization of the membrane to +30 mV 4. K+ ion flow out of the neuron increases 5. repolarization of the membrane

-->Use the graph below to identify the phases of the action potential. Drag the appropriate labels to their respective targets.

1. rest 2. depolarization 3. peak 4. repolarization 5. hyperpolarization

How is an action potential propagated along an axon?

An influx of sodium ions from the current action potential depolarizes the adjacent area

Which is a similarity between spatial summation and temporal summation?

Both allow sub threshold graded potentials to trigger an action potential

-->Drag and drop each of the terms at the left to the correct statement at the right.

DEPOLARIZATION: sodium ions are moving in, and the membrane potential is becoming less negative than the resting membrane potential REPOLARIZATION: potassium ions are moving out, and the membrane potential is becoming more negative as it moves back toward the resting membrane potential HYPERPOLARIZATION: potassium ions are moving out, and the membrane potential is becoming more negative than the resting membrane potential

Why does the action potential only move away from the cell body?

The areas that have had the action potential are refractory to a new action potential

The velocity of the action potential is fastest in which of the following axons?

a small myelinated axon

During an action potential, when does sodium ion permeability begin to significantly decline?

at the peak of depolarization

In this experiment, which stimulus causes the membrane potential to reach the threshold value?

stimulus 3

During an action potential, the rapid decrease in sodium ion permeability and the simultaneous and rapid increase in potassium ion permeability is responsible for __________.

the repolarization phase