Answer: twice.
- A twice
- B once
- C three times
- D four times
Correct answer: A. twice
Explanation: In double circulation the blood goes through the heart twice per full circuit.
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.