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

4. Tissues & Histology

Introduction to Muscle Tissue

Anatomy & Physiology

4. Tissues & Histology

Introduction to Muscle Tissue

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Multiple Choice

When a skeletal muscle is at rest, which protein is bound to the actin filaments?

Actinase

Myosin

Tropomyosin

Troponin

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Verified step by step guidance

Step 1: Begin by understanding the structure of a skeletal muscle fiber. Skeletal muscle fibers contain myofibrils, which are composed of repeating units called sarcomeres. Sarcomeres are the functional units of muscle contraction and consist of actin (thin filaments) and myosin (thick filaments).

Step 2: Learn about the proteins associated with actin filaments. Actin filaments are regulated by two key proteins: tropomyosin and troponin. Tropomyosin is a long, rope-like protein that wraps around the actin filament, while troponin is a complex of three subunits that interacts with tropomyosin and actin.

Step 3: Understand the role of tropomyosin in a resting muscle. When a skeletal muscle is at rest, tropomyosin covers the binding sites on actin filaments, preventing myosin from attaching to actin and initiating contraction.

Step 4: Clarify the role of troponin. Troponin is responsible for regulating the position of tropomyosin. When calcium ions bind to troponin during muscle activation, it causes a conformational change that moves tropomyosin away from the actin binding sites, allowing myosin to bind and initiate contraction.

Step 5: Conclude that in a resting skeletal muscle, tropomyosin is the protein bound to actin filaments, blocking the myosin-binding sites and maintaining the muscle in a relaxed state.