Cardiac Action Potential Phases

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What is the main function of the right side of the heart?

To receive oxygenated blood from the pulmonary circulation

To pump blood to the body against low resistance and under low pressure (correct)

To pump blood to the lungs against high resistance and under high pressure

To pump blood to the systemic circulation through the aorta

What is the main function of the left side of the heart?

To receive deoxygenated blood from the systemic circulation

To pump blood to the lungs against high resistance and under high pressure (correct)

To pump blood to the pulmonary circulation through the pulmonary artery

To pump blood to the body against low resistance and under low pressure

What is the name of the phase in the cardiac cycle when the heart muscle contracts to eject blood?

Repolarization

Systole (correct)

Diastole

Depolarization

What is the name of the phase in the cardiac cycle when the heart muscle relaxes to be filled with blood?

Diastole Signup and view all the answers

What is the name of the wall of the left ventricle?

Thicker than the right ventricle Signup and view all the answers

What is the name of the blood vessels that carry deoxygenated blood from the body to the right atrium?

Superior and inferior vena cava Signup and view all the answers

What is the function of the atrium in the heart?

Serving mainly as a reservoir of blood Signup and view all the answers

During which phase of the action potential does depolarization occur in cardiac muscle fibers?

Phase 0 Signup and view all the answers

What is the resting membrane potential of cardiac muscle fibers?

-90 mV Signup and view all the answers

Which ion channels are responsible for the depolarization phase in cardiac muscle fibers?

Voltage-gated Na+ channels Signup and view all the answers

What characterizes the repolarization phase of the action potential in cardiac muscle fibers?

Triphasic and slow process Signup and view all the answers

What is the specific role of ventricular fibers in the heart's action potential?

Generation of action potentials Signup and view all the answers

During which phase of the action potential does the membrane potential return to +10 mV due to the outflow of K+ through K+ channels?

Phase 2: The Plateau Signup and view all the answers

What contributes to the prolonged plateau of the action potential in ventricular fibers?

Continuous efflux of K+ Signup and view all the answers

Which phase is characterized by the closure of slow calcium-sodium channels and unopposed outflow of K+ until repolarization is complete?

Phase 3: Rapid repolarization to RMP Signup and view all the answers

What role do slow calcium-sodium channels play during the plateau phase of the action potential?

Balancing the inflow of Ca++ & Na+ with the outflow of K+ Signup and view all the answers

What is the membrane potential during Phase 3 of the action potential?

-50 mV Signup and view all the answers

What prevents the heart from developing sustained, tetanic contractions during the absolute refractory period?

Closure of slow calcium-sodium channels Signup and view all the answers

Cardiac Action Potential Phases

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