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

What event occurs in the heart as the atrioventricular (AV) valves are closing?

The ventricles are relaxing and filling with blood.

The atria are relaxing and filling with blood.

The semilunar valves are opening to allow blood into the arteries.

The ventricles begin to contract, marking the start of ventricular systole.

Previous problemNext problem

Verified step by step guidance

Step 1: Understand the function of the atrioventricular (AV) valves. These valves are located between the atria and ventricles and prevent backflow of blood into the atria when the ventricles contract.

Step 2: Recall the phases of the cardiac cycle. The heart undergoes systole (contraction) and diastole (relaxation). Ventricular systole refers to the contraction of the ventricles, which forces blood into the arteries.

Step 3: Recognize the sequence of valve actions during ventricular systole. As the ventricles begin to contract, the pressure inside them increases, causing the AV valves to close to prevent backflow into the atria.

Step 4: Note the relationship between the AV valves and semilunar valves. When the AV valves close, the semilunar valves (located at the exits of the ventricles) open to allow blood to flow into the arteries.

Step 5: Conclude that the closing of the AV valves marks the start of ventricular systole, as the ventricles begin to contract and pump blood into the arteries.