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

Sliding Filament Theory and the Sacromere

Anatomy & Physiology

9. Muscle Tissue

Sliding Filament Theory and the Sacromere

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Multiple Choice

According to the sliding filament model, binding sites on actin open when which of the following occurs?

ATP is hydrolyzed by myosin

Myosin heads detach from actin

Calcium ions bind to troponin

Acetylcholine is released at the neuromuscular junction

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Verified step by step guidance

Understand the sliding filament model: This model explains how muscle contraction occurs at the molecular level. It involves the interaction between actin and myosin filaments within the sarcomere, the functional unit of muscle fibers.

Identify the role of calcium ions: Calcium ions play a critical role in muscle contraction. When a muscle fiber is stimulated, calcium ions are released from the sarcoplasmic reticulum into the cytoplasm.

Explain the function of troponin: Troponin is a regulatory protein complex attached to tropomyosin on the actin filament. Tropomyosin blocks the binding sites on actin, preventing myosin from attaching. Calcium ions bind to troponin, causing a conformational change that moves tropomyosin away from the binding sites on actin.

Relate calcium binding to actin binding sites: Once tropomyosin is shifted, the binding sites on actin are exposed, allowing myosin heads to attach and initiate the cross-bridge cycle, which is essential for muscle contraction.

Clarify the incorrect options: ATP hydrolysis by myosin provides energy for the movement of myosin heads but does not directly open actin binding sites. Myosin heads detaching from actin occurs during the relaxation phase. Acetylcholine is a neurotransmitter that triggers the initial muscle fiber stimulation but does not directly affect actin binding sites.