Answer: Electrical activity of the heart through a cardiac cycle.
- A Volume of blood ejected with each heartbeat
- B Electrical activity of the heart through a cardiac cycle
- C Mechanical pumping force generated by the ventricles
- D Rate of oxygen use by the cardiac muscle
Correct answer: B. Electrical activity of the heart through a cardiac cycle
Explanation: An ECG is a graphical record of the electrical changes that occur during a cardiac cycle, showing characteristic P, QRS and T waves.
A single ECG cycle: the P wave marks atrial depolarisation (contraction signal), the large QRS complex marks ventricular depolarisation, and the T wave marks ventricular repolarisation (recovery) before the next cycle begins.
Concept context
Blood, lymph, the heart, the cardiac cycle, blood pressure, and ECG. High NEET weightage.