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 statement describes the mechanism of muscle contraction?

The myosin heads bind to actin filaments, forming cross-bridges and pulling the actin filaments toward the center of the sarcomere.

Calcium ions are released from the sarcoplasmic reticulum and bind to myosin, causing it to detach from actin.

The sarcomere lengthens as the actin and myosin filaments move apart, resulting in muscle contraction.

ATP is hydrolyzed to ADP and phosphate, which directly causes the actin filaments to slide past the myosin filaments.

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Verified step by step guidance

Begin by understanding the structure of a sarcomere, the basic unit of a muscle fiber, which consists of actin and myosin filaments.

Recognize the role of calcium ions in muscle contraction. Calcium ions are released from the sarcoplasmic reticulum and bind to troponin, not myosin, which causes a conformational change that exposes binding sites on actin filaments.

Learn about the cross-bridge cycle: Myosin heads bind to the exposed sites on actin filaments, forming cross-bridges. This is a crucial step in muscle contraction.

Understand the role of ATP in muscle contraction. ATP binds to myosin, causing it to detach from actin. ATP is then hydrolyzed to ADP and inorganic phosphate, which provides energy for the myosin head to pivot and pull the actin filament toward the center of the sarcomere.

Conclude with the sliding filament theory: Muscle contraction occurs as actin filaments slide past myosin filaments, shortening the sarcomere and thus the muscle fiber.