Question:
Which of the following is known as Dobie's Line?
Which of the following is known as Dobie's Line?
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Z-line = boundary of sarcomere and anchoring point of actin filaments.
Updated On: Jun 20, 2026
- M - Line
- Z - Line
- A - Line
- H - Line
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The Correct Option is B
Solution and Explanation
Step 1: Understanding muscle fiber structure.
Skeletal muscle fibers are made up of repeating functional units called sarcomeres. These sarcomeres are responsible for muscle contraction. Each sarcomere has distinct structural lines like Z-line, M-line, A-band and H-zone. These structures help in identifying muscle organization.
Step 2: What is Dobie's line?
Dobie's line is an alternative historical term used for the Z-line in muscle physiology. It represents the boundary of a sarcomere and anchors actin filaments. It is an important structural marker in muscle histology.
Step 3: Role of Z-line in sarcomere.
The Z-line defines the starting and ending point of a sarcomere. Thin actin filaments are attached to it on both sides. During muscle contraction, Z-lines move closer to each other. This helps in shortening of the muscle fiber.
Step 4: Evaluating other options.
M-line is present at the center of the sarcomere and holds myosin filaments. A-band represents the region of myosin overlap and does not define boundaries. H-zone is the central lighter region within the A-band. None of these correspond to Dobie's line.
Step 5: Conceptual clarification.
Since Dobie's line refers specifically to the structural boundary of sarcomere, only Z-line matches this definition. It is widely accepted in histology and physiology. Therefore, correct identification is essential for muscle structure questions.
Step 6: Final conclusion.
Thus, Dobie's line is correctly identified as the Z-line of the sarcomere.
Skeletal muscle fibers are made up of repeating functional units called sarcomeres. These sarcomeres are responsible for muscle contraction. Each sarcomere has distinct structural lines like Z-line, M-line, A-band and H-zone. These structures help in identifying muscle organization.
Step 2: What is Dobie's line?
Dobie's line is an alternative historical term used for the Z-line in muscle physiology. It represents the boundary of a sarcomere and anchors actin filaments. It is an important structural marker in muscle histology.
Step 3: Role of Z-line in sarcomere.
The Z-line defines the starting and ending point of a sarcomere. Thin actin filaments are attached to it on both sides. During muscle contraction, Z-lines move closer to each other. This helps in shortening of the muscle fiber.
Step 4: Evaluating other options.
M-line is present at the center of the sarcomere and holds myosin filaments. A-band represents the region of myosin overlap and does not define boundaries. H-zone is the central lighter region within the A-band. None of these correspond to Dobie's line.
Step 5: Conceptual clarification.
Since Dobie's line refers specifically to the structural boundary of sarcomere, only Z-line matches this definition. It is widely accepted in histology and physiology. Therefore, correct identification is essential for muscle structure questions.
Step 6: Final conclusion.
Thus, Dobie's line is correctly identified as the Z-line of the sarcomere.
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