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

Which of the following is most directly required to initiate the coupling of myosin to actin in the sliding filament theory?

Calcium ions

Sodium ions

Potassium ions

ATP

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Verified step by step guidance

Understand the sliding filament theory: This theory explains how muscles contract by the sliding of actin and myosin filaments past each other, which shortens the muscle fiber.

Identify the role of calcium ions: Calcium ions are crucial in muscle contraction as they bind to troponin, a regulatory protein on the actin filament, causing a conformational change that exposes the binding sites for myosin on the actin filaments.

Recognize the role of ATP: ATP is necessary for the detachment of myosin heads from actin after a power stroke and for the re-cocking of the myosin heads, but it is not directly responsible for the initial coupling of myosin to actin.

Consider the roles of sodium and potassium ions: These ions are primarily involved in generating action potentials and maintaining the resting membrane potential, rather than directly facilitating the coupling of myosin to actin.

Conclude that calcium ions are most directly required: Since calcium ions are responsible for exposing the binding sites on actin for myosin attachment, they are the most directly required ions for initiating the coupling of myosin to actin in muscle contraction.