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

Electrical Conduction System of the Heart

Anatomy & Physiology

18. The Heart

Electrical Conduction System of the Heart

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Multiple Choice

Which events occur at the beginning of ventricular systole?

Opening of the semilunar valves

Closure of the atrioventricular valves

Atrial contraction

Filling of the ventricles

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Verified step by step guidance

Understand the cardiac cycle: The cardiac cycle consists of two main phases, systole and diastole. Systole refers to the contraction phase, while diastole refers to the relaxation phase.

Identify the phases of ventricular systole: Ventricular systole is the phase where the ventricles contract to pump blood out of the heart. It begins right after atrial systole (atrial contraction) and involves two main events: isovolumetric contraction and ventricular ejection.

Recognize the role of valves: During the cardiac cycle, the heart valves ensure unidirectional blood flow. The atrioventricular (AV) valves (tricuspid and mitral) separate the atria from the ventricles, while the semilunar valves (aortic and pulmonary) separate the ventricles from the major arteries.

Determine the events at the start of ventricular systole: At the beginning of ventricular systole, the ventricles start to contract, causing the pressure within them to rise. This pressure increase leads to the closure of the atrioventricular valves to prevent backflow into the atria.

Differentiate between valve actions: The closure of the AV valves marks the start of isovolumetric contraction, where the ventricles contract with no volume change because all valves are closed. The semilunar valves open later in the cycle when ventricular pressure exceeds arterial pressure, allowing blood to be ejected.