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

Why does atrial repolarization not appear as a separate wave on an electrocardiogram (ECG)?

It is masked by the larger QRS complex.

It is too small to be detected by ECG electrodes.

It occurs at the same time as the T wave.

It is represented by the P wave.

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Verified step by step guidance

Understand the components of an electrocardiogram (ECG): The ECG is a graphical representation of the electrical activity of the heart. Key waves include the P wave (atrial depolarization), QRS complex (ventricular depolarization), and T wave (ventricular repolarization).

Recognize that atrial repolarization is a physiological process: After the atria depolarize (P wave), they repolarize to return to their resting state. This repolarization generates electrical activity, but it is not prominently visible on the ECG.

Consider the timing of atrial repolarization: Atrial repolarization occurs during the QRS complex, which represents ventricular depolarization. The electrical activity of the QRS complex is much larger and masks the smaller signal of atrial repolarization.

Understand the relative size of electrical signals: The electrical activity generated by atrial repolarization is too small to be detected separately by ECG electrodes, especially when compared to the larger QRS complex.

Conclude that atrial repolarization is not represented as a separate wave: It is not visible on the ECG because it is overshadowed by the QRS complex and does not produce a distinct wave.