Why is the P wave smaller than the QRS complex?

Related questions

1. What is happening in the heart during the T wave?
2. What does it mean if you have an inverted T wave?
3. What is normal P value in ECG?
4. How do you calculate the QRS interval on an ECG?
5. What is a normal P QRS T axis?
6. How do you measure QRS complex?
7. What is wide QRS tachycardia?

Tags

1. #ventricular
2. #represents
3. #through
4. #atrial
5. #impulse
6. #complex
7. #atria
8. #which
9. #because
10. #smaller
11. #spreads
12. #muscle
13. #ventricles
14. #corresponds
15. #depolarization