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

During which component of an electrocardiogram (ECG) do the ventricles contract?

T wave

QRS complex

P wave

U wave

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Verified step by step guidance

Understand the components of an electrocardiogram (ECG): An ECG is a graphical representation of the electrical activity of the heart. It consists of several waves and complexes, each representing different phases of the cardiac cycle.

Identify the QRS complex: The QRS complex is a series of three graphical deflections seen on an ECG. It represents the depolarization of the ventricles, which is the electrical activity that triggers ventricular contraction.

Recognize the significance of the QRS complex: During the QRS complex, the ventricles contract, pumping blood to the lungs and the rest of the body. This is a crucial part of the cardiac cycle, as it ensures the circulation of oxygenated blood.

Differentiate between the other components: The P wave represents atrial depolarization, leading to atrial contraction. The T wave represents ventricular repolarization, which is the recovery phase after contraction. The U wave is less commonly seen and its significance is not fully understood.

Conclude that the QRS complex is the correct answer: Based on the understanding of the ECG components, the QRS complex is the phase during which the ventricles contract.