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

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

The first heart sound represents which portion of the cardiac cycle?

Closure of the semilunar valves

Opening of the semilunar valves

Closure of the atrioventricular valves

Opening of the atrioventricular valves

Previous problemNext problem

Verified step by step guidance

Understand the cardiac cycle: The cardiac cycle consists of systole (contraction) and diastole (relaxation) phases. During these phases, different valves open and close to regulate blood flow through the heart.

Identify the heart sounds: The heart produces two main sounds, often described as 'lub' and 'dub'. The first heart sound, 'lub', is associated with the closure of certain valves.

Focus on the first heart sound: The first heart sound occurs at the beginning of systole when the ventricles contract. This sound is produced by the closure of the atrioventricular (AV) valves, which include the mitral and tricuspid valves.

Differentiate between valve types: The atrioventricular valves separate the atria from the ventricles, while the semilunar valves are located at the exits of the ventricles (aortic and pulmonary valves). The first heart sound is specifically related to the AV valves.

Conclude the association: The first heart sound is associated with the closure of the atrioventricular valves, marking the start of ventricular contraction and preventing backflow of blood into the atria.