CHAPTER 12 The Cardiovascular System 257 The waves of the ECG are P wave: SA nod
ID: 3505746 • Letter: C
Question
CHAPTER 12 The Cardiovascular System 257 The waves of the ECG are P wave: SA node depolarizes the which chambers and the atria contracL QRS complex includes the Q. R and S waves. This complex mainly represent ventricles, which leads to ventricular contraction. Why is the QRS complex greater depolarization of the than the P wave? T wave is the repolarization of the ventrides. Why can't we see a wave for atrial repolarization? ECG helps to analyze problems such as: Cardiac arrihythmia is any abnormal pattern of cardiac electrical activity Large P wave indicates an enlarged Flat T wave suggests insufficien Long Q-T interval may occur if there has been myocardial damage. is reaching the heart muscle. Review Time! 1 Place a raomber from 1 to 5 in the blank before each sep of the pathway to itndicate the correct order of the conduction of nerve impulses of the heart's comduction system AV bundle (bundle of His) AV node Internodal pathway -Purkinje fibers SA node Provide a bricf anower for eack of the following questions about heart fionction II. 1. What valves close during "lubb and "dupp? 2. What does one cardiac cycle represent? 3. What wave on an ECG corresponds to an impulse sent from the SA node? 4. Why is there a delay when the AV node fires an impulse? 5. Why is the QRS complex larger than the P wave? 6. What is an ECG? 7. Where is the SA node located? 8. What is the function of the SA node? 9. What does an impulse from the AV node cause to happen? 10. What does the T wave on an ECG represent? 11. What are the atria doing during atrial systole? 12. Which node sends an impulse to promote atrial systole? 13. What happens during ventricular systole? 14. When the atria are in systole, what is happening with the ventricles?Explanation / Answer
Ans-1
Sinoatrial (SA) node depolarize wall of both atria so atria contract
Ans-2
Muscle mass of ventricle chamber are greater than atria that's why QRS complex is larger than P wave.
Ans-3
Atrial repolarization simultaneously taking places with ventricle depolarization that's why not it visible in ECG.
Ans-4
Larger P wave indicate enlarged atria
Ans-5
Flat T wave suggest insufficient blood reaching to cardiac muscle
Review time:
1. SA node-1, Internodal pathways-2, AV node-3, Bundle of his-4, Purkinje fibre-5