Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

18. The Heart

Electrocardiogram (ECG)

Anatomy & Physiology

18. The Heart

Electrocardiogram (ECG)

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Multiple Choice

Which portion of the ECG cycle overlaps with the expected ventricular contraction (systole)?

P wave

QRS complex

U wave

T wave

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Verified step by step guidance

Step 1: Understand the components of the ECG cycle. The ECG (electrocardiogram) represents the electrical activity of the heart. Key components include the P wave, QRS complex, T wave, and sometimes a U wave.

Step 2: Recall the physiological events associated with each component. The P wave corresponds to atrial depolarization, the QRS complex represents ventricular depolarization, and the T wave reflects ventricular repolarization. The U wave is less commonly seen and its significance is debated.

Step 3: Connect electrical activity to mechanical events. Ventricular contraction (systole) begins shortly after ventricular depolarization, which is represented by the QRS complex on the ECG.

Step 4: Eliminate incorrect options. The P wave is associated with atrial activity, not ventricular contraction. The T wave represents repolarization, which occurs after systole. The U wave is not directly related to systole.

Step 5: Conclude that the QRS complex overlaps with the expected ventricular contraction (systole), as it represents the electrical signal that triggers the mechanical contraction of the ventricles.