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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

What happens after the ventricles of the heart complete their contraction?

The atria contract, pushing blood into the ventricles.

The ventricles begin to fill with blood from the pulmonary veins.

The atrioventricular valves open, allowing blood to flow from the atria to the ventricles.

The semilunar valves close, preventing backflow of blood into the ventricles.

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Verified step by step guidance

Understand the cardiac cycle: The heart operates in a cycle of contraction and relaxation, known as systole and diastole, respectively.

Identify the phase in question: The problem asks about the events following ventricular contraction, which is the systole phase.

Recognize the role of valves: During ventricular systole, blood is ejected into the arteries, and the semilunar valves (aortic and pulmonary) are open.

Determine what happens after contraction: Once the ventricles complete their contraction, they begin to relax, entering diastole.

Explain the valve action: As the ventricles relax, the pressure within them drops, causing the semilunar valves to close. This prevents the backflow of blood from the arteries into the ventricles.