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Questions and Answers
Which of the following is true about the T wave in a normal ECG?
Which of the following is true about the T wave in a normal ECG?
- It is composed of three separate waves
- It is known as a repolarization wave (correct)
- It is a depolarization wave
- It is caused by electrical potentials generated during atrial contraction
What is the QRS complex in a normal ECG caused by?
What is the QRS complex in a normal ECG caused by?
- Potentials generated when the ventricles depolarize before contraction (correct)
- Potentials generated when the ventricles repolarize after contraction
- Potentials generated as the ventricles recover from the state of depolarization
- Potentials generated when the atria depolarize before atrial contraction begins
What happens to the potential difference between two electrodes during repolarization of a cardiac muscle fiber?
What happens to the potential difference between two electrodes during repolarization of a cardiac muscle fiber?
- It returns to zero (correct)
- It becomes more negative on the inside and more positive on the outside
- It remains the same as during depolarization
- It becomes more positive on the inside and more negative on the outside
What is the main difference between depolarization waves and repolarization waves in an ECG?
What is the main difference between depolarization waves and repolarization waves in an ECG?
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What is the T wave in a normal ECG caused by?
What is the T wave in a normal ECG caused by?
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What is the QRS complex in a normal ECG composed of?
What is the QRS complex in a normal ECG composed of?
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Study Notes
T Wave in Normal ECG
- Represents repolarization of the ventricles in the heart.
- Typically appears as a positive deflection following the QRS complex.
- In a healthy ECG, the T wave is asymmetrical, with a slower rise and a steeper descent.
QRS Complex in Normal ECG
- Caused by the depolarization of the ventricles, leading to their contraction.
- Represents a rapid influx of sodium ions into cardiac muscle cells.
- Composed of three distinct waves: Q wave (initial negative deflection), R wave (tall positive deflection), and S wave (subsequent negative deflection).
Potential Difference During Repolarization
- The potential difference between two electrodes decreases as potassium ions exit the cardiac muscle fiber.
- This change helps return the membrane potential to its resting state.
Differences Between Depolarization and Repolarization Waves
- Depolarization waves (e.g., QRS complex) are rapid and result in muscle contraction.
- Repolarization waves (e.g., T wave) are slower, indicating relaxation of the cardiac muscle.
Cause of the T Wave
- Caused by the outflow of potassium ions from cardiac muscle cells during ventricular repolarization.
- Reflects the electrical activity as the heart muscle resets for the next cycle.
Composition of the QRS Complex
- Made up of Q wave, R wave, and S wave, each representing different phases of ventricular depolarization.
- Typically lasts between 0.06 to 0.1 seconds in a normal ECG.
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