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

Which of the following correctly lists the phases of the cardiac cycle in order, starting immediately after ventricular filling?

Atrial systole → isovolumetric contraction → ventricular ejection → isovolumetric relaxation

Isovolumetric relaxation → isovolumetric contraction → ventricular ejection → atrial systole

Isovolumetric contraction → ventricular ejection → isovolumetric relaxation → atrial systole

Ventricular ejection → isovolumetric contraction → isovolumetric relaxation → atrial systole

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Verified step by step guidance

Step 1: Understand the cardiac cycle phases. The cardiac cycle consists of sequential phases that describe the mechanical events of the heart during one heartbeat. These phases include ventricular filling, atrial systole, isovolumetric contraction, ventricular ejection, isovolumetric relaxation, and diastole.

Step 2: Identify the starting point. The problem specifies starting immediately after ventricular filling, which means the next phase is atrial systole. Atrial systole involves the contraction of the atria to push additional blood into the ventricles.

Step 3: Follow the sequence of events. After atrial systole, the ventricles begin to contract without ejecting blood yet, leading to isovolumetric contraction. This phase is characterized by a rise in ventricular pressure while all heart valves remain closed.

Step 4: Continue to ventricular ejection. Once the pressure in the ventricles exceeds the pressure in the arteries, the semilunar valves open, and blood is ejected from the ventricles into the pulmonary artery and aorta.

Step 5: Conclude with isovolumetric relaxation. After ventricular ejection, the ventricles relax, and the pressure drops. The semilunar valves close, and all valves remain closed briefly before the cycle repeats with atrial systole.