Cardiac Action potential, MC multiple answer
This assignment consists of multiple-choice questions that focus on the cardiac action potential. Each question may have more than one correct answer, and it is important to select all that apply. The questions are designed to test your understanding of the phases, ion movements, and physiological significance of the cardiac action potential.
Group 1
This section contains multiple-choice questions focusing on the 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 membrane 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
Closure of Na+ channels
Question 1d
During which phase does the plateau phase occur in the cardiac action potential?
Phase 0
Phase 1
Phase 2
Phase 3
Phase 4
Question 1e
Which of the following statements about Phase 2 of the cardiac action potential is correct?
It involves the influx of Ca2+ ions
It involves the efflux of K+ ions
It is characterized by a plateau in membrane potential
It is the phase of rapid depolarization
It is the phase of rapid repolarization
Question 1f
Which channels are primarily responsible for the rapid depolarization in Phase 0?
Voltage-gated Na+ channels
Voltage-gated K+ channels
Voltage-gated Ca2+ channels
Ligand-gated Cl- channels
Voltage-gated Mg2+ channels
Question 1g
What characterizes Phase 3 of the cardiac action potential?
Efflux of K+ ions
Influx of Na+ ions
Influx of Ca2+ ions
Closure of Ca2+ channels
Opening of Na+ channels
Question 1h
Which phase is associated with the resting membrane potential in cardiac cells?
Phase 0
Phase 1
Phase 2
Phase 3
Phase 4
Question 1i
During which phase do voltage-gated Ca2+ channels open?
Phase 0
Phase 1
Phase 2
Phase 3
Phase 4
Question 1j
Which of the following are true about the refractory period in cardiac action potentials?
It prevents tetanus in cardiac muscle
It allows time for the heart to refill with blood
It occurs during the plateau phase
It is shorter than in skeletal muscle
It is when the heart muscle is most excitable
Question 1k
What is the role of the Na+/K+ pump in cardiac cells?
Maintains the resting membrane potential
Restores ion gradients after action potentials
Directly causes depolarization
Directly causes repolarization
Increases intracellular Ca2+ concentration
Question 1l
Which phases of the cardiac action potential are primarily responsible for the refractory period?
Phase 0
Phase 1
Phase 2
Phase 3
Phase 4
Question 1m
Which of the following statements about the cardiac action potential is correct?
It is longer than the action potential in skeletal muscle
It is shorter than the action potential in neurons
It involves a plateau phase not present in neurons
It is initiated by the autonomic nervous system
It is responsible for the contraction of cardiac muscle
Question 1n
What is the significance of the plateau phase in cardiac action potentials?
Prevents premature contractions
Allows sustained contraction for effective pumping
Increases the speed of conduction
Decreases the duration of the action potential
Facilitates rapid depolarization
Question 1o
Which ion movement is primarily responsible for the initial repolarization in Phase 1?
Efflux of K+ ions
Influx of Na+ ions
Influx of Ca2+ ions
Efflux of Cl- ions
Efflux of Na+ ions
Question 1p
Which of the following are true regarding the ionic basis of the cardiac action potential?
Na+ influx causes depolarization
Ca2+ influx maintains the plateau phase
K+ efflux causes repolarization
Cl- influx causes depolarization
Mg2+ influx maintains the plateau phase
Question 1q
What is the primary function of the plateau phase in cardiac action potentials?
To prolong the refractory period
To allow time for ventricular filling
To prevent arrhythmias
To ensure coordinated contraction
To increase heart rate
Question 1r
Which of the following are involved in the termination of the cardiac action potential?
Closure of Ca2+ channels
Opening of K+ channels
Closure of Na+ channels
Opening of Na+ channels
Closure of K+ channels
Question 1s
Which of the following are true about the ionic currents during the cardiac action potential?
Na+ current is responsible for the upstroke
Ca2+ current maintains the plateau
K+ current is responsible for repolarization
Cl- current is responsible for depolarization
Mg2+ current is responsible for the plateau
Question 1t
Which phases of the cardiac action potential are associated with the refractory period?
Phase 0
Phase 1
Phase 2
Phase 3
Phase 4
Question 1u
Which of the following statements about the cardiac action potential is correct?
It is longer than the action potential in skeletal muscle
It is shorter than the action potential in neurons
It involves a plateau phase not present in neurons
It is initiated by the autonomic nervous system
It is responsible for the contraction of cardiac muscle
Question 1v
Which ion channels are primarily responsible for the plateau phase?
Voltage-gated Ca2+ channels
Voltage-gated Na+ channels
Voltage-gated K+ channels
Ligand-gated Cl- channels
Voltage-gated Mg2+ channels
Question 1w
What is the role of the Na+/K+ pump in cardiac cells?
Maintains the resting membrane potential
Restores ion gradients after action potentials
Directly causes depolarization
Directly causes repolarization
Increases intracellular Ca2+ concentration
Question 1x
Which of the following are true regarding the ionic basis of the cardiac action potential?
Na+ influx causes depolarization
Ca2+ influx maintains the plateau phase
K+ efflux causes repolarization
Cl- influx causes depolarization
Mg2+ influx maintains the plateau phase
Question 1y
What is the primary function of the plateau phase in cardiac action potentials?
To prolong the refractory period
To allow time for ventricular filling
To prevent arrhythmias
To ensure coordinated contraction
To increase heart rate
Question 1z
Which of the following are involved in the termination of the cardiac action potential?
Closure of Ca2+ channels
Opening of K+ channels
Closure of Na+ channels
Opening of Na+ channels
Closure of K+ channels
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