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 Heart2h 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

Cardiac Cycle

Anatomy & Physiology

18. The Heart

Cardiac Cycle

Previous problemNext problem

Struggling with Anatomy & Physiology?

Join thousands of students who trust us to help them ace their exams!Watch the first video

Multiple Choice

During which phase of the cardiac cycle do you hear the second heart sound?

Ventricular filling.

Isometric contraction.

Isovolumetric relaxation.

Ventricular ejection.

Previous problemNext problem

Verified step by step guidance

Understand the cardiac cycle phases: The cardiac cycle consists of several phases including ventricular filling, isometric contraction, ventricular ejection, and isovolumetric relaxation.

Identify the heart sounds: The heart sounds are typically referred to as 'lub' (first heart sound) and 'dub' (second heart sound). The 'lub' is associated with the closure of the atrioventricular valves, while the 'dub' is associated with the closure of the semilunar valves.

Relate heart sounds to cardiac cycle phases: The second heart sound ('dub') occurs when the semilunar valves close, which happens during the isovolumetric relaxation phase.

Analyze the isovolumetric relaxation phase: During this phase, the ventricles relax after the blood has been ejected, and the semilunar valves close to prevent backflow of blood into the ventricles, producing the second heart sound.

Conclude the relationship: The second heart sound is heard during the isovolumetric relaxation phase of the cardiac cycle, as this is when the semilunar valves close.