Podcast
Questions and Answers
What happens during the isovolumetric contraction phase of the cardiac cycle?
What happens during the isovolumetric contraction phase of the cardiac cycle?
- Ventricular blood pressure drops, allowing blood to flow into the aorta.
- Heart muscle remains relaxed, and no significant pressure changes occur.
- Ventricles contract, elevating blood pressure above the atria, closing the atrioventricular valves. (correct)
- Atrial pressure exceeds ventricular pressure, causing the atrioventricular valves to close.
Which segment of the cardiac cycle corresponds to the atrial systole?
Which segment of the cardiac cycle corresponds to the atrial systole?
- Segment between T and P waves.
- Segment between P and QRS waves. (correct)
- Segment between QRS and T waves.
- Segment during isovolumetric relaxation.
What is indicated by the T wave on an electrocardiogram?
What is indicated by the T wave on an electrocardiogram?
- Atrial repolarization.
- Atrial depolarization.
- Ventricular depolarization.
- Ventricular repolarization. (correct)
What initiates the transition from passive to active ventricular filling?
What initiates the transition from passive to active ventricular filling?
Why can't the plateau phase or SA node action potentials be visually detected on an EKG?
Why can't the plateau phase or SA node action potentials be visually detected on an EKG?
Which phases occur during the segment from QRS to T waves in the cardiac cycle?
Which phases occur during the segment from QRS to T waves in the cardiac cycle?
What occurs during ventricular filling in the passive stage?
What occurs during ventricular filling in the passive stage?
What indicate the closing of the atrioventricular valves during ventricular systole?
What indicate the closing of the atrioventricular valves during ventricular systole?
Flashcards
Plateau Phase
Plateau Phase
The period of sustained depolarization in a cardiac muscle cell action potential, characterized by a prolonged influx of calcium ions. This phase is critical for maintaining the contraction of the heart.
What does the electrocardiogram depict?
What does the electrocardiogram depict?
The electrocardiogram (EKG or ECG) is a recording of the electrical activity of the heart. It depicts the spread of depolarization and repolarization waves across the heart muscle, providing information about the rhythm, rate, and overall health of the heart.
Why can't plateau or SA node action potentials be seen on EKG?
Why can't plateau or SA node action potentials be seen on EKG?
The plateau phase is too subtle to be detected on an EKG because it's a small change in the electrical activity of the heart. The SA node action potentials are too small in number to be picked up by the EKG.
What changes are occurring in the heart during the isovolumetric contraction phase?
What changes are occurring in the heart during the isovolumetric contraction phase?
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What determines when the ventricular filling phase moves from passive to active stages?
What determines when the ventricular filling phase moves from passive to active stages?
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What stage(s) of the cardiac cycle occurs during the segment between QRS and T waves?
What stage(s) of the cardiac cycle occurs during the segment between QRS and T waves?
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What stage(s) of the cardiac cycle occurs during the segment between P and QRS waves?
What stage(s) of the cardiac cycle occurs during the segment between P and QRS waves?
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What stage(s) of the cardiac cycle occurs during the segment between T and P waves?
What stage(s) of the cardiac cycle occurs during the segment between T and P waves?
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Study Notes
Plateau Phase and Systole
- Plateau phase action potentials are too subtle to show on an EKG.
- SA node action potentials are small and occur in a small number of cells, making them undetectable on EKG.
EKG Depiction
- EKG shows depolarizations and repolarizations as they spread through the heart, seen through the skin.
Isovolumetric Contraction Phase
- Ventricles begin systole with low blood pressure.
- Contraction elevates blood pressure, closing atrioventricular valves (S1).
- Ventricular pressure rises.
- When ventricular pressure surpasses aortic pressure (80 mmHg), ventricular ejection begins.
Ventricular Filling Phase Transition
- The firing of the SA node initiates the transition from passive to active ventricular filling.
- The SA node's action potential spreads to the atria and, through a plateau, causes atrial systole (active stage).
Cardiac Cycle Stages (QRS-T Wave Segment)
- Isovolumetric contraction and ventricular ejection occur during this period.
- This period roughly corresponds to ventricular systole.
Cardiac Cycle Stages (P-QRS Wave Segment)
- Active stage of ventricular filling occurs during this period.
- This period roughly corresponds to atrial systole.
Cardiac Cycle Stages (T-P Wave Segment)
- Isovolumetric relaxation and passive ventricular filling occur.
- Ventricular repolarization (T wave) signifies the end of ventricular contraction (systole) and beginning of diastole.
- The passive filling phase follows isovolumetric relaxation.
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Description
Test your knowledge on the stages of the cardiac cycle, including the plateau phase, isovolumetric contraction, and ventricular filling. This quiz addresses key concepts from physiology and EKG interpretation relevant to heart function. Challenge yourself with questions about action potentials and their significance in cardiac events!
