GEMP - Action Potential 🔥

Action Potential

Quiz Type

Practice

Subject

Physiology

Level

Level 300

Questions

9 questions

Created By

Premio Quest

Quick Rules

Time limit: 4 minutes
Multiple attempts are not allowed
All questions must be answered to submit

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Question 1 of 9

Question 1

Basic multiple choice Remembering understanding

A researcher is studying a newly identified type of neuron that requires a membrane potential of -55 mV to initiate action potentials. If the neuron is consistently activated by a sub-threshold stimulus, what physiological significance does this have on the frequency of action potentials?

The neuron will continuously fire action potentials at a high frequency.

The neuron will fire action potentials sporadically over time.

The neuron will never reach action potentials but can increase its frequency based on stronger stimuli.

Correct

The neuron will spontaneously depolarize and reach action potential without external stimulus.

Explanation

The neuron can respond to stronger stimuli by increasing its firing frequency, but a sub-threshold stimulus cannot trigger action potentials.

Question 2

Basic multiple choice Remembering understanding

During an experiment, it was observed that after a neuron depolarizes, the membrane potential returns to its resting state. Which mechanism is primarily responsible for this repolarization phase?

Increased permeability to sodium ions.

Decreased permeability to potassium ions.

Increased permeability to potassium ions.

Correct

Activation of calcium channels.

Explanation

Repolarization occurs via the opening of potassium channels that allow K⁺ ions to exit, restoring the negative membrane potential.

Question 3

Basic multiple choice Remembering understanding

Consider a scenario where a patient has a damaged refractory period due to a neurological condition. What potential cardiovascular implication could arise from this dysfunction?

Increased unidirectional signal propagation through the heart.

Decreased frequency of heartbeats leading to bradycardia.

Potential for arrhythmias due to overlapping action potentials.

Correct

Enhanced action potential duration resulting in a stable heart rhythm.

Explanation

A damaged refractory period may lead to inappropriate timing of action potentials, which can cause arrhythmias.

Question 4

Basic multiple choice Remembering understanding

How does the all-or-nothing principle of action potentials relate to the concept of stimulus intensity in the context of neuronal coding for sensory input?

Stimulus intensity correlates with the amplitude of individual action potentials.

Formal integration of action potentials leads to varying centroid positions.

Different stimuli can generate action potentials with varying frequencies, encoding the intensity.

Correct

Higher intensities cause action potentials to happen more frequently without changing their form.

Explanation

Stimulus intensity is encoded by the frequency of action potentials, not by their amplitude, aligning with the all-or-nothing principle.

Question 5

Basic multiple choice Remembering understanding

In a study, researchers observed that in skeletal muscle cells, action potentials are critical for muscle contraction. If a drug inhibits the release of calcium ions from the sarcoplasmic reticulum, what is the expected outcome regarding muscle contraction?

Muscles will contract stronger and faster.

Muscle contraction will occur as normal since calcium is not involved.

Muscle contraction will be weakened or may not occur at all.

Correct

Muscle contractions will initiate without action potentials.

Explanation

Calcium ions are essential for muscle contraction; inhibition of their release would result in inadequate muscle contraction.

Question 6

Basic multiple choice Remembering understanding

If a scientist varies the sodium concentration outside a neuron while maintaining all other conditions constant, what effect would this have on the resting membrane potential, and how would it influence the threshold potential?

Increasing external sodium concentration would make the resting potential more negative.

Decreasing external sodium concentration would raise the threshold potential.

Correct

Changes in sodium concentration do not affect resting or threshold potentials.

Increasing sodium concentration will decrease the threshold potential.

Explanation

Lowering sodium concentration outside the neuron makes it harder to depolarize, thus requiring a greater threshold potential to generate an action potential.

Question 7

Basic multiple choice Remembering understanding

Analyzing the process of depolarization, which factor is essential for the rapid change observed during action potential initiation in neurons?

A large number of potassium ions exiting the cell.

A sudden influx of calcium ions into the cell.

A rapid influx of sodium ions into the neuron.

Correct

Gradual decrease of potassium permeability over a long duration.

Explanation

Depolarization is primarily characterized by the quick influx of sodium ions when sodium channels open after reaching threshold potential.

Question 8

Basic multiple choice Remembering understanding

In a clinical scenario, a patient is experiencing frequent muscle spasms. What could be the physiological reason behind the condition if the patient has an elevated frequency of action potentials in motor neurons?

Increased release of neurotransmitters leading to sustained muscle contraction.

Correct

Inability for the muscle to relax due to prolonged potassium flow out of the cell.

Consistent sodium influx preventing muscle contraction altogether.

The refractory period is effectively shortened thus allowing a single action potential to dominate.

Explanation

An elevated frequency of action potentials can lead to an increased release of neurotransmitters, causing sustained contraction and spasms.

Question 9

Basic multiple choice Remembering understanding

Considering the misconception around 'all-or-nothing' responses in action potentials, how might the frequency of action potentials influence neural encoding of specific stimuli?

Higher frequency indicates a reduced signal strength due to fatigue.

Frequency directly affects the type of neurotransmitter released.

The rate of action potentials contributes to how the brain interprets stimulus intensity.

Correct

Every action potential must lead to neurotransmitter release, regardless of frequency.

Explanation

The frequency of action potentials is instrumental in signaling to the brain the intensity of the stimulus received, aligning with neural coding principles.