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What does an electrocardiogram (ECG) primarily measure?
The resting ECG can provide information about previous heart attacks.
True
What is the primary function of Bachmann's bundle in the heart?
To conduct electrical impulses between the two atria
During diastole, the ______ valves are opened allowing blood to fill the ventricles.
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Match the following ECG waves with their corresponding events:
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Which of the following can be detected through an ECG?
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Superficial mechanical activities of the heart are typically recorded by an ECG.
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What physiological state occurs when semilunar valves are closed in the heart?
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During which phase are the semilunar valves closed and the AV valves opened?
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The AV valves are always closed during ventricular systole.
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What is the role of the semilunar valves during the period of ejection?
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In the period of isovolumic relaxation, blood flowing back toward the ventricles causes the __________ valves to close.
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Which electrode is considered the neutral point in ECG recordings?
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Match the ECG electrode with its location:
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It is important to attach electrodes to different parts of the body for accurate ECG results.
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What occurs during the diastole phase known as passive ventricular filling?
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Where is the V1 electrode placed?
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The SA node assumes command if the AV node is damaged.
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What do the extremity leads I, II, and III measure?
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V4 is placed in the _____ intercostal space in the nipple line.
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Which of the following is a possible result of heart block?
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Match the heart rhythm problems with their descriptions:
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The 3 channel ECG is adequate for detecting ST elevation.
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What is a primary function of ECG leads?
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Study Notes
ECG Basics
- ECG represents millions of cardiomyocyte action potentials
Action Potential: Myocyte
- The ECG represents the sum of the action potentials of millions of cardiomyocytes
Conducting System of Heart
- The conducting system of the heart is responsible for initiating and coordinating heart contractions
- Bachmann's Bundle and internodal fibers connect the SA node to the AV node
The different ECG waves
- The different ECG waves represent different stages of the cardiac cycle
Depolarization and Repolarization at the Ventricles
- Depolarization and repolarization occur during the cardiac cycle
ECG
- An ECG records the electrical activity of your heart at rest.
- An ECG provides information about your heart rate and rhythm, and shows if there is enlargement of the heart due to high blood pressure (hypertension) or evidence of a previous heart attack (myocardial infarction).
Diastole: Passive ventricular filling
- AV valves open
- Blood flows into the relaxed ventricles
Diastole: Active ventricular filling
- Atria contract
- Complete ventricular filling
Systole: Period of isovolumic contraction
- Ventricular contraction causes the AV valves to close
- Semilunar valves remain closed during this period
Systole: Period of ejection
- Continued ventricular contraction pushes blood out of the ventricles
- Semilunar valves open
Diastole: Period of isovolumic relaxation
- Blood flowing back causes the semilunar valves to close.
- AV valves closed
The ECG electrodes
- Ten electrodes are used to record the electrical activity of the heart
- Four extremity electrodes:
- LA (left arm)
- RA (right arm)
- N (Neutral, on the right leg)
- F (foot, on the left leg)
- Six chest electrodes:
- V1 (4th intercostal space, right of the sternum)
- V2 (4th intercostal space, left of the sternum)
- V3 (between V2 and V4)
- V4 (5th intercostal space in the nipple line)
- V5 (between V4 and V6)
- V6 (midaxillary line on the same height as V4)
The Bipolar Leads:
- 3 or 4 ECG electrodes used in a 3-channel ECG
- Each electrode picks up electrical signals from the heart
- Enough information for rhythm-monitoring
Some Heart Rhythm Problems
- Conduction deficits result from damage to conducting pathways
- Damaged SA node or internodal pathways lead to the AV node assuming command
Heart Block
- Damage to the AV node partially or totally releases the ventricles from the control of the SA node
- Ventricles beat at their own, slower, rate
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Description
This quiz covers the fundamentals of electrocardiography (ECG) and the heart's conducting system. Learn about the action potentials of cardiomyocytes, different ECG waves, and the phases of the cardiac cycle including depolarization and repolarization. Ideal for students studying cardiac physiology and ECG interpretation.
