Answer: Twice per circuit (to lungs AND to body).
- A Only once per circuit, directly to the body
- B Twice per circuit (to lungs AND to body)
- C In two directions at the same simultaneous moment
- D As many as four separate times per single circuit
Correct answer: B. Twice per circuit (to lungs AND to body)
Explanation: Humans have double circulation: pulmonary (heart to lungs and back) and systemic (heart to body and back). Blood passes through the heart twice per 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.