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

9. Muscle Tissue

Steps of Muscle Contraction

Anatomy & Physiology

9. Muscle Tissue

Steps of Muscle Contraction

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Multiple Choice

Which of the following occurs during the power stroke of muscle contraction?

The myosin head returns to its original position, ready for another cycle.

ATP binds to the myosin head, causing it to detach from the actin filament.

Calcium ions are released from the sarcoplasmic reticulum.

The myosin head pivots, pulling the actin filament toward the center of the sarcomere.

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Verified step by step guidance

Understand the context of muscle contraction: Muscle contraction involves a cycle of events known as the cross-bridge cycle, which includes the attachment of myosin heads to actin filaments, the power stroke, detachment, and re-cocking of the myosin head.

Identify the role of the power stroke: During the power stroke, the myosin head pivots and pulls the actin filament toward the center of the sarcomere. This action is crucial for muscle contraction as it shortens the sarcomere, leading to the shortening of the muscle fiber.

Differentiate between the steps of the cross-bridge cycle: The power stroke is distinct from other steps such as ATP binding, which causes the myosin head to detach from actin, and the release of calcium ions, which initiates the contraction process by exposing binding sites on actin.

Recognize the sequence of events: The power stroke occurs after the myosin head has attached to the actin filament and before ATP binds to the myosin head to cause detachment.

Conclude with the correct action during the power stroke: The myosin head pivots, pulling the actin filament toward the center of the sarcomere, which is the correct description of what occurs during the power stroke of muscle contraction.