Multiple Choice Questions (MCQs)
- What does the P wave represent in an ECG?
a) Ventricular depolarization
b) Atrial depolarization
c) Ventricular repolarization
d) Atrial repolarization
Answer: b) Atrial depolarization - What is the primary significance of the QRS complex?
a) Atrial systole
b) Ventricular depolarization
c) Ventricular repolarization
d) Ventricular diastole
Answer: b) Ventricular depolarization - Which ECG wave represents ventricular repolarization?
a) P wave
b) QRS complex
c) T wave
d) U wave
Answer: c) T wave - Which ECG segment represents the time between the end of ventricular depolarization and the beginning of ventricular repolarization?
a) PR segment
b) ST segment
c) TP segment
d) QT interval
Answer: b) ST segment - What is the duration of the P-R interval in cattle?
a) 0.10 seconds
b) 0.18 seconds
c) 0.13 seconds
d) 0.30 seconds
Answer: b) 0.18 seconds - The formula for calculating heart rate from the R-R interval is:
a) Heart rate = 100 ÷ R-R interval
b) Heart rate = R-R interval × 60
c) Heart rate = 60 ÷ R-R interval
d) Heart rate = R-R interval ÷ 100
Answer: c) Heart rate = 60 ÷ R-R interval - What does the U wave represent when present?
a) Ventricular depolarization
b) Repolarization of Purkinje fibers or ventricular papillary muscles
c) Atrial repolarization
d) Electrical activity of the AV node
Answer: b) Repolarization of Purkinje fibers or ventricular papillary muscles - Which interval reflects the time from ventricular depolarization to complete repolarization?
a) P-R interval
b) Q-T interval
c) R-R interval
d) P-P interval
Answer: b) Q-T interval - Which species has the longest P-R interval duration?
a) Horse
b) Cattle
c) Swine
d) Dog
Answer: a) Horse - What is the average heart rate for sheep and goats?
a) 70 beats/min
b) 100 beats/min
c) 35 beats/min
d) 130 beats/min
Answer: b) 100 beats/min
Fill in the Blanks
- The ________ wave in an ECG represents ventricular repolarization.
Answer: T - The time between two successive P waves is called the ________ interval.
Answer: P-P - The ________ complex in an ECG represents ventricular depolarization.
Answer: QRS - The ________ point is the junction between the QRS complex and the ST segment.
Answer: J - The heart rate per minute can be calculated using the formula ________.
Answer: 60 ÷ R-R interval
True or False
- Atrial repolarization is visible as a separate wave on an ECG.
Answer: False - The PR segment represents AV nodal depolarization.
Answer: True - The QT interval includes both ventricular depolarization and repolarization.
Answer: True - In horses, the QRS interval is shorter than the PR interval.
Answer: True - The ST segment appears as a flat line on the ECG.
Answer: True
Subjective Questions
- Describe the components of the QRS complex and their significance.
Answer:- Q wave: The first negative deflection, indicating the initiation of ventricular depolarization as it spreads from the left septum to the right septum.
- R wave: The positive deflection, representing the conduction of impulses from the Purkinje fibers to the epicardial surface of the ventricles.
- S wave: The negative deflection following the R wave, reflecting impulse conduction at the base of the heart.
The QRS complex is crucial as it represents the electrical activity that precedes ventricular contraction, ensuring effective blood ejection.
- Explain the importance of the PR and QT intervals in clinical diagnosis.
Answer:- PR Interval: Reflects the time for excitation to travel from the SA node to the Purkinje system, including AV nodal delay. Abnormalities in this interval may indicate AV block or delayed conduction.
- QT Interval: Represents the time from the initiation of ventricular depolarization to the completion of ventricular repolarization. Prolongation of the QT interval can signal electrolyte imbalances, myocardial ischemia, or arrhythmias.
These intervals are vital for assessing cardiac conduction and diagnosing potential abnormalities.