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 region of the ECG corresponds to the electrical changes associated with atrial repolarization?

P wave

T wave

It is masked by the QRS complex

QRS complex

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Verified step by step guidance

Step 1: Begin by understanding the components of an ECG (Electrocardiogram). The ECG is a graphical representation of the electrical activity of the heart. It consists of several waves: the P wave, QRS complex, and T wave, each corresponding to specific electrical events in the heart.

Step 2: Recall the physiological events associated with each wave. The P wave represents atrial depolarization (the electrical activity that triggers atrial contraction). The QRS complex represents ventricular depolarization (the electrical activity that triggers ventricular contraction). The T wave represents ventricular repolarization (the recovery phase of the ventricles).

Step 3: Consider atrial repolarization. Atrial repolarization is the recovery phase of the atria after depolarization. However, this electrical activity is relatively small and occurs simultaneously with the QRS complex.

Step 4: Understand why atrial repolarization is not visible on the ECG. The electrical signal of atrial repolarization is masked by the much larger electrical activity of the QRS complex, which represents ventricular depolarization.

Step 5: Conclude that the region of the ECG corresponding to atrial repolarization is not directly visible because it is obscured by the QRS complex.