Human Anatomy and Physiology : Help with Action Potential Physiology

Study concepts, example questions & explanations for Human Anatomy and Physiology

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Example Questions

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Example Question #11 : General Neuron Physiology

A stimulus applied to a neuronal membrane that causes its potential to become more positive is __________. A stimulus that moves the potential closer to 0 is __________.

Possible Answers:

depolarization . . . hyperpolarization

hyperpolarization . . . depolarization

hyperpolarization . . . hyperpolarization

hyperpolarization . . . resting membrane potential

depolarization . . . depolarization

Correct answer:

hyperpolarization . . . depolarization

Explanation:

If an already positive membrane potential becomes more positive, it is becoming hyperpolarized because the electrical difference between the inside and outside of the cell is getting larger. On the other hand, a stimulus that moves the potential difference closer to 0 is depolarizing because it is decreasing the difference in electrical potential between the inside and outside of the cell.

Example Question #11 : Neural Physiology

The presence of __________ dramatically increases the speed at which an action potential moves along an axon.

Possible Answers:

neurilemma

myelin

a capsule

plasma protein

Correct answer:

myelin

Explanation:

Myelin helps to increase resistance along the axon, which helps to propagate the action potential along the axon.

Example Question #11 : Help With Action Potential Physiology

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

1. inactivation of Na channels and activation of K channels

2. depolarization to threshold

3. return to normal permeability

4. activation of Na channels

What is the proper sequence of these events?

Possible Answers:

2,4,3,1

1,2,3,4

2,4,1,3

4,3,2,1

Correct answer:

2,4,1,3

Explanation:

In order to have an action potential, you must have a depolarization. Na channels must close before K channels open

Example Question #13 : Neural Physiology

Which part of the neuron generates the action potential?

Possible Answers:

axon

cell body

axon hillock

dendrites

nucleus

Correct answer:

axon hillock

Explanation:

The action potential of a neuron is generate at the axon hillock and is propagated down the axon and to the terminal branches where it will synapse with the dendrites of the next neuron.

Example Question #12 : Help With Action Potential Physiology

Which of the following describes the influx of  ions into the neuron?

Possible Answers:

none of these

hyperpolarization

repolarization

depolarization

polarization

Correct answer:

depolarization

Explanation:

The influx of positive sodium ions into the neuron is known as depolarization. This is the loss of negative charge that occurs when positive sodium passes through the neural membrane and enters the neuron.

Example Question #13 : Help With Action Potential Physiology

When the neuron becomes depolarized, which of the following events takes place?

Possible Answers:

None of these will occur.

efflux of potassium ions

efflux of sodium ions

influx of sodium ions

influx of potassium ions

Correct answer:

influx of sodium ions

Explanation:

Depolarization is when the neuron becomes more positive by gaining positively charged ions, specifically sodium ions. During depolarization the sodium ion channels open and sodium ions enter the neuron, reducing the membrane potential to roughly +35 mV.

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