Answer: Pericardium.
- A Pleura
- B Peritoneum
- C Endocardium
- D Pericardium
Correct answer: D. Pericardium
Explanation: The pericardium is the double-layered sac surrounding the heart, and the pericardial fluid within it reduces friction during heartbeats.
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.