Cardiac Action Potential: Multiple Choice Questions
This assignment consists of multiple-choice questions focused on the cardiac action potential. Each question may have multiple correct answers. Carefully read each question and select all the correct answers. This exercise is designed to test your understanding of the phases, ionic movements, and physiological significance of cardiac action potentials.
Group 1
This section contains multiple-choice questions on the topic of cardiac action potential. Each question may have more than one correct answer. Select all that apply.
Question 1a
Which phases are part of the cardiac action potential?
Phase 0 - Rapid depolarization
Phase 1 - Initial repolarization
Phase 2 - Plateau
Phase 3 - Rapid repolarization
Phase 4 - Resting potential
Phase 5 - Hyperpolarization
Question 1b
Which ions are primarily involved in the cardiac action potential?
Sodium (Na+)
Potassium (K+)
Calcium (Ca2+)
Chloride (Cl-)
Magnesium (Mg2+)
Question 1c
What occurs during Phase 0 of the cardiac action potential?
Rapid influx of Na+ ions
Efflux of K+ ions
Influx of Ca2+ ions
Efflux of Cl- ions
Influx of Mg2+ ions
Question 1d
During which phase does the plateau occur in the cardiac action potential?
Phase 0
Phase 1
Phase 2
Phase 3
Phase 4
Question 1e
What is the primary ion movement during Phase 3 of the cardiac action potential?
Efflux of K+ ions
Influx of Na+ ions
Influx of Ca2+ ions
Efflux of Cl- ions
Influx of Mg2+ ions
Question 1f
Which of the following statements are true about the cardiac action potential?
It is longer than the action potential in skeletal muscle.
It involves a plateau phase.
It does not involve calcium ions.
It is shorter than the action potential in neurons.
It is initiated by the opening of potassium channels.
Question 1g
What role does calcium play in the cardiac action potential?
Contributes to the plateau phase
Triggers muscle contraction
Causes rapid depolarization
Causes rapid repolarization
Is not involved in the cardiac action potential
Question 1h
Which channels are primarily responsible for the depolarization phase of the cardiac action potential?
Voltage-gated sodium channels
Voltage-gated potassium channels
Voltage-gated calcium channels
Ligand-gated chloride channels
Voltage-gated magnesium channels
Question 1i
Which of the following are characteristics of the resting potential in cardiac cells?
Maintained by the Na+/K+ pump
Negative inside relative to outside
Positive inside relative to outside
Maintained by the Ca2+ pump
No ion movement occurs
Question 1j
What is the significance of the refractory period in cardiac action potentials?
Prevents tetanus in cardiac muscle
Allows time for the heart to refill with blood
Allows for rapid successive action potentials
Increases the strength of contraction
Decreases the strength of contraction
Question 1k
Which of the following factors can influence the cardiac action potential duration?
Heart rate
Ion channel mutations
Temperature
Blood pressure
Oxygen levels
Question 1l
Which of the following are true regarding the sodium-potassium pump in cardiac cells?
It helps maintain the resting membrane potential.
It pumps 3 Na+ out and 2 K+ in.
It pumps 2 Na+ out and 3 K+ in.
It is active during the action potential.
It does not require ATP.
Question 1m
What happens during the initial repolarization phase (Phase 1) of the cardiac action potential?
Closure of Na+ channels
Opening of K+ channels
Opening of Ca2+ channels
Closure of K+ channels
Opening of Na+ channels
Question 1n
Which phases of the cardiac action potential involve calcium ion movement?
Phase 2
Phase 0
Phase 1
Phase 3
Phase 4
Question 1o
Which of the following are true about the plateau phase of the cardiac action potential?
It is due to the influx of Ca2+ ions.
It prolongs the action potential.
It is due to the efflux of Na+ ions.
It shortens the action potential.
It occurs during Phase 3.
Question 1p
What is the role of potassium ions during the cardiac action potential?
Responsible for repolarization
Contributes to resting membrane potential
Causes depolarization
Responsible for the plateau phase
Not involved in the action potential
Question 1q
Which of the following statements are true about the refractory period in cardiac cells?
It prevents the heart from undergoing tetanus.
It ensures unidirectional propagation of the action potential.
It allows for immediate re-excitation of the heart muscle.
It shortens the duration of the action potential.
It is not present in cardiac cells.
Question 1r
What occurs during the plateau phase of the cardiac action potential?
Influx of Ca2+ ions
Efflux of K+ ions
Influx of Na+ ions
Efflux of Na+ ions
Influx of Cl- ions
Question 1s
Which of the following are effects of calcium channel blockers on cardiac action potentials?
Decrease the duration of the plateau phase
Reduce the force of cardiac contraction
Increase the rate of depolarization
Increase the duration of the plateau phase
Increase the force of cardiac contraction
Question 1t
Which of the following are true about the ionic basis of cardiac action potentials?
Na+ influx causes rapid depolarization
K+ efflux causes repolarization
Ca2+ influx contributes to the plateau phase
Cl- influx causes depolarization
Mg2+ influx contributes to the plateau phase
Question 1u
What is the primary effect of digitalis on cardiac action potentials?
Increases intracellular calcium
Increases the force of contraction
Decreases the duration of the action potential
Decreases intracellular sodium
Decreases the force of contraction
Question 1v
Which of the following are true regarding the role of sodium ions in cardiac action potentials?
Responsible for the rapid depolarization phase
Contributes to the plateau phase
Responsible for repolarization
Not involved in the action potential
Contributes to the resting membrane potential
Question 1w
What is the effect of hyperkalemia on cardiac action potentials?
Decreases the resting membrane potential
Increases the excitability of cardiac cells
Increases the resting membrane potential
Decreases the excitability of cardiac cells
Has no effect on cardiac action potentials
Question 1x
Which of the following are true about the effects of hypocalcemia on cardiac action potentials?
Prolongs the duration of the action potential
Decreases the force of contraction
Shortens the duration of the action potential
Increases the force of contraction
Has no effect on cardiac action potentials
Question 1y
Which of the following are true about the role of the autonomic nervous system in modulating cardiac action potentials?
Sympathetic stimulation increases heart rate
Parasympathetic stimulation decreases heart rate
Sympathetic stimulation decreases heart rate
Parasympathetic stimulation increases heart rate
The autonomic nervous system has no effect on heart rate
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