Q6. The figure below shows one sarcomere. Fill in the boxes below with the correct structure:

Background

Topic: Muscle Anatomy – Sarcomere Structure

This question tests your understanding of the microscopic anatomy of skeletal muscle, specifically the arrangement of myofilaments within a sarcomere. The sarcomere is the basic contractile unit of muscle fiber.

Key Terms and Concepts:

• Sarcomere: The segment between two Z discs; the functional unit of muscle contraction.

• Myofilaments: Actin (thin filament) and myosin (thick filament) are the main proteins involved in contraction.

• Z disc: Defines the boundaries of a sarcomere.

• M line: The center of the sarcomere, where thick filaments are anchored.

• A band: The region containing the entire length of the thick filaments.

• I band: The region containing only thin filaments.

Step-by-Step Guidance

1. Examine the diagram and identify the boundaries of the sarcomere. The vertical lines at each end represent the Z discs.

2. Locate the thick filaments (usually shown in red) and thin filaments (often blue or yellow). The thick filaments are anchored at the M line in the center, while the thin filaments are attached to the Z discs.

3. Identify the regions labeled in the diagram. The top boxes likely correspond to the Z disc and M line, while the side boxes may indicate the A band, I band, and H zone.

4. Recall that the A band includes the entire length of the thick filaments, the I band is the area with only thin filaments, and the H zone is the central region with only thick filaments.

5. Use your knowledge of sarcomere structure to match each box to the correct anatomical term. Review your textbook or notes for visual cues if needed.

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