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

In a fully contracted sarcomere, the H zone:

contains only thin filaments

disappears as the thin filaments overlap the thick filaments completely

remains unchanged in width

widens as the sarcomere shortens

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Verified step by step guidance

Understand the structure of a sarcomere: A sarcomere is the functional unit of a muscle fiber, consisting of thick filaments (myosin) and thin filaments (actin). Key regions include the A band, I band, H zone, and Z discs.

Define the H zone: The H zone is the central region of the sarcomere that contains only thick filaments (myosin) and no overlapping thin filaments (actin). It is located within the A band.

Analyze what happens during muscle contraction: During contraction, the thin filaments slide past the thick filaments, moving toward the M line (center of the sarcomere). This sliding action reduces the distance between the Z discs, shortening the sarcomere.

Determine the effect on the H zone: As the thin filaments move inward and overlap with the thick filaments, the H zone becomes progressively smaller. In a fully contracted sarcomere, the thin filaments completely overlap the thick filaments, causing the H zone to disappear.

Conclude the correct answer: Based on the above analysis, the H zone disappears as the thin filaments overlap the thick filaments completely in a fully contracted sarcomere.