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 theory, which event occurs during muscle contraction?

Myosin filaments shorten while actin filaments remain stationary.

The sarcomere lengthens as actin and myosin filaments move apart.

Actin filaments slide past myosin filaments, shortening the sarcomere.

Calcium ions are released, causing the sarcomere to expand.

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Verified step by step guidance

Understand the sliding filament theory: This theory explains the mechanism of muscle contraction at the molecular level. It involves the interaction between actin and myosin filaments within the sarcomere, the functional unit of a muscle fiber.

Identify the role of actin and myosin filaments: During contraction, actin filaments slide past myosin filaments. This sliding action shortens the sarcomere, which is the region between two Z-discs in a muscle fiber.

Recognize the role of calcium ions: Calcium ions are released from the sarcoplasmic reticulum in response to a nerve signal. These ions bind to troponin, causing a conformational change that moves tropomyosin away from the binding sites on actin, allowing myosin heads to attach to actin.

Understand the cross-bridge cycle: Myosin heads bind to actin, forming cross-bridges. Using energy from ATP hydrolysis, the myosin heads pivot, pulling the actin filaments toward the center of the sarcomere. This action is repeated in a cycle, leading to sarcomere shortening.

Clarify the incorrect options: Myosin filaments do not shorten; they remain stationary while actin filaments slide. The sarcomere does not lengthen during contraction; it shortens. Calcium ions facilitate contraction but do not cause the sarcomere to expand.