GEMP - Action Potential

Action Potential Introduction An action potential is a rapid, temporary change in the membrane potential of a neuron or muscle cell, which allows for the transmission of electrical signals in the body. Understanding action potentials is fundamental for medical students as they play a critical role in nervous system function, muscle contraction, and communication between cells, impacting vario...

Quiz Type

Practice

Subject

Physiology

Level

Level 300

Questions

8 questions

Created By

Premio Quest

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Time limit: 4 minutes
Multiple attempts are not allowed
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Question 1 of 8

Question 1

Basic multiple choice Remembering understanding

What is the typical value of the resting membrane potential in neurons?

-40 mV

-70 mV

Correct

-90 mV

0 mV

Explanation

The resting membrane potential is typically around -70 mV in neurons, establishing the baseline necessary for action potentials.

Question 2

Basic multiple choice Remembering understanding

What occurs when a neuron's membrane reaches the threshold potential?

Potassium channels open

The resting potential stabilizes

Voltage-gated sodium channels open

Correct

Calcium ions are released

Explanation

When the membrane reaches the threshold potential, voltage-gated sodium channels open, allowing an influx of Na⁺ ions that initiates the action potential.

Question 3

Basic multiple choice Remembering understanding

During which phase does repolarization occur?

When K⁺ ions flow into the cell

When Na⁺ permeability decreases

After the membrane has depolarized

Correct

During the resting state

Explanation

Repolarization occurs after depolarization, involving the closure of sodium channels and the opening of potassium channels to restore the negative charge inside the cell.

Question 4

Basic multiple choice Remembering understanding

Why is the refractory period important for neuron function?

It prevents all-or-nothing responses

It allows for multiple action potentials to occur simultaneously

It ensures unidirectional signal propagation

Correct

It increases sodium permeability

Explanation

The refractory period ensures that action potentials only propagate in one direction along the neuron, thus maintaining the integrity of signal transmission.

Question 5

Basic multiple choice Remembering understanding

What misconception is often associated with action potentials?

All action potentials vary in size based on stimulus strength

Action potentials are always initiated by synaptic transmission

Only large stimuli can trigger action potentials

Action potentials have the same amplitude regardless of frequency

Correct

Explanation

While the frequency of action potentials can vary with stimulus strength, the peak amplitude of action potentials is consistent for a given neuron.

Question 6

Basic multiple choice Remembering understanding

What regulates the rhythmic contractions of the heart?

Neurotransmitter release

Calcium ion concentration

Action potentials from cardiac pacemaker cells

Correct

Sodium ion permeability

Explanation

Cardiac pacemaker cells generate action potentials that regulate the heart's rhythmic contractions, ensuring proper circulation.

Question 7

Basic multiple choice Remembering understanding

How is the action potential related to neural signal transmission?

It prevents neurotransmitter release

It travels down the axon triggering calcium channels

It allows for communication between neurons

Correct

It stabilizes the resting membrane potential

Explanation

Action potentials are essential for the communication between neurons, allowing them to transmit signals effectively.

Question 8

Basic multiple choice Remembering understanding

In the context of action potentials, what does the term 'all-or-nothing' refer to?

The membrane potential cannot change below resting potential

Once threshold is reached, the action potential either occurs or does not occur

Correct

Action potentials vary size based on stimulus strength

Neurons can fire multiple action potentials at once

Explanation

The 'all-or-nothing' principle means that once the threshold potential is reached, an action potential occurs fully or not at all, rather than in varying magnitudes.