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Questions and Answers
Which phase of the ventricular action potential is characterized by a balance between Na+ and Ca++ influx and K+ outflux?
What is the primary cause of the initial rapid depolarization in the ventricular action potential?
Which phase of the ventricular action potential marks the late rapid repolarization?
What is the resting membrane potential in the context of ventricular action potential?
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What property of cardiac muscle ensures that it cannot go into a sustained state of contraction?
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Which type of muscle contraction involves an increase in tension without a change in muscle length?
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What is the main function of the T-tubule during cardiac action potential?
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What happens to cardiac muscle contraction if T-tubule calcium ion entry is impaired?
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Which part of the heart is known as the pacemaker?
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What is the primary characteristic of rhythmicity in cardiac muscle?
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Which component of the heart's conduction system is critical for spreading depolarization rapidly?
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What is the rate of autorhythmicity in the Purkinje fibers?
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What is excitability in the context of cardiac muscle?
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What characterizes Phase 0 of the ventricular action potential?
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Which of the following is true about resting membrane potential (RPM)?
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What is the main ionic basis of ventricular action potential?
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Which property allows excitable cells like cardiac muscle to transmit electrochemical impulses?
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What defines Phase 1 of the ventricular action potential?
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Study Notes
Ventricular Action Potential
- The phase characterized by a balance between Na+ and Ca++ influx and K+ outflux is the plateau phase.
- The primary cause of the initial rapid depolarization is the rapid influx of Na+ ions.
- The phase that marks the late rapid repolarization is Phase 3.
Cardiac Muscle Characteristics
- The resting membrane potential is approximately -90mV.
- The property that ensures cardiac muscle cannot go into a sustained state of contraction is the refractory period.
- Isometric contraction, which involves an increase in tension without a change in muscle length, is a type of muscle contraction.
T-Tubules and Calcium Ion Entry
- The main function of T-tubules during cardiac action potential is to allow rapid transmission of the action potential to the sarcoplasmic reticulum.
- Impaired T-tubule calcium ion entry would lead to decreased cardiac muscle contraction.
Cardiac Conduction System
- The sinoatrial (SA) node is known as the pacemaker.
- The primary characteristic of rhythmicity in cardiac muscle is the ability to generate rhythmic electrical impulses spontaneously.
- The Purkinje fibers are critical for spreading depolarization rapidly.
- The rate of autorhythmicity in Purkinje fibers is approximately 30-40 beats per minute.
Excitability and Ventricular Action Potential
- Excitability refers to the ability of a cell to respond to a stimulus and generate an action potential.
- Phase 0 of the ventricular action potential is characterized by rapid depolarization due to Na+ influx.
- The resting membrane potential (RMP) is the voltage at which the cardiac muscle is at rest.
- The main ionic basis of ventricular action potential is the influx of Na+ and Ca++ ions and the efflux of K+ ions.
- The property that allows excitable cells like cardiac muscle to transmit electrochemical impulses is excitability.
- Phase 1 of the ventricular action potential is characterized by early rapid repolarization due to K+ efflux.
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Description
Test your knowledge on the ionic basis of ventricular action potential phases in the heart. From the initial rapid depolarization to the late rapid repolarization, this quiz covers the key mechanisms involved in each phase.
