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 step constitutes the power stroke of muscle contraction?

Calcium ions bind to troponin, causing a conformational change in tropomyosin.

The sarcoplasmic reticulum releases calcium ions into the cytosol.

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

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

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Verified step by step guidance

Understand the sequence of events in muscle contraction, which involves the interaction between actin and myosin filaments within the sarcomere.

Recognize that the power stroke is a specific step in the muscle contraction cycle where the myosin head pivots and pulls the actin filament toward the center of the sarcomere.

Identify the role of calcium ions in muscle contraction. Calcium ions bind to troponin, causing a conformational change in tropomyosin, which exposes the binding sites on actin for myosin.

Note that ATP is crucial for muscle contraction and relaxation. ATP binds to the myosin head, causing it to detach from the actin filament, allowing the cycle to repeat.

The power stroke is characterized by the movement of the myosin head, which is powered by the hydrolysis of ATP, resulting in the sliding of actin filaments past myosin filaments, leading to muscle contraction.