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 one of the following binds calcium ions in a smooth muscle, causing contraction?

actin

myosin

calmodulin

tropomyosin

troponin

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Verified step by step guidance

Understand the role of calcium ions in muscle contraction: Calcium ions are crucial for muscle contraction as they interact with specific proteins to initiate the contraction process.

Identify the proteins involved in smooth muscle contraction: In smooth muscle, the key proteins involved are calmodulin, actin, myosin, tropomyosin, and troponin.

Recognize the function of calmodulin: Calmodulin is a calcium-binding messenger protein that plays a pivotal role in smooth muscle contraction by activating myosin light-chain kinase (MLCK) when bound to calcium ions.

Differentiate between skeletal and smooth muscle proteins: Unlike skeletal muscle, smooth muscle does not use troponin for calcium binding. Instead, calmodulin serves this function in smooth muscle.

Conclude that calmodulin is the protein that binds calcium ions in smooth muscle, leading to contraction by activating MLCK, which in turn phosphorylates myosin, allowing it to interact with actin.