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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 these events occurs first in muscle fiber contraction?

Binding of acetylcholine to receptors on the muscle fiber

Power stroke of the myosin heads

Detachment of myosin heads from actin

Release of calcium ions from the sarcoplasmic reticulum

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Verified step by step guidance

Understand the sequence of events in muscle contraction, which is initiated by a nerve impulse.

Recognize that the first event in muscle contraction is the binding of acetylcholine, a neurotransmitter, to receptors on the muscle fiber. This occurs at the neuromuscular junction.

Once acetylcholine binds to its receptors, it triggers an action potential in the muscle fiber, leading to depolarization.

Depolarization causes the sarcoplasmic reticulum to release calcium ions into the cytosol of the muscle cell.

Calcium ions bind to troponin, causing a conformational change that moves tropomyosin away from actin's binding sites, allowing myosin heads to attach to actin and initiate the power stroke.