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

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Multiple Choice

At what point in the cardiac cycle does the semilunar valve open?

During atrial systole

During ventricular systole

During ventricular diastole

During isovolumetric relaxation

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Verified step by step guidance

Understand the cardiac cycle phases: The cardiac cycle consists of atrial systole, ventricular systole, and ventricular diastole.

Identify the role of the semilunar valves: These valves prevent backflow from the arteries into the ventricles and open to allow blood to be ejected from the heart.

Recognize when the semilunar valves open: They open during ventricular systole when the pressure in the ventricles exceeds the pressure in the arteries.

Differentiate between the phases: During atrial systole, the atria contract to fill the ventricles. During ventricular diastole, the ventricles relax and fill with blood. During isovolumetric relaxation, the ventricles relax but the semilunar valves remain closed.

Conclude that the semilunar valves open during ventricular systole, allowing blood to flow from the ventricles into the aorta and pulmonary artery.