Answer: It initiates electrical impulses that set heart rate (~72 bpm).
- A It forms the largest muscular chamber within the four chambers of the heart
- B It initiates electrical impulses that set heart rate (~72 bpm)
- C It generates the strongest contractile force of any region in the myocardium
- D It regulates systemic blood pressure directly via baroreceptor reflexes
Correct answer: B. It initiates electrical impulses that set heart rate (~72 bpm)
Explanation: SA node (in right atrium wall) generates spontaneous electrical impulses at ~72/min, setting the heart rate. It is the natural pacemaker.
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.