Answer: atria.
- A atria
- B ventricles
- C valves
- D arteries
Correct answer: A. atria
Explanation: The atria are the upper receiving chambers of the heart.
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.