Multiple Choice
What are the folds in the sarcolemma at the neuromuscular junction called?
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4. Tissues & Histology
Introduction to Muscle Tissue
Multiple Choice
The region of the sarcomere containing both thick and thin filaments is the:
A
I band
B
A band
C
H zone
D
Z disc
Verified step by step guidance1
Step 1: Understand the structure of a sarcomere, which is the functional unit of a muscle fiber. It is composed of repeating units of thick filaments (myosin) and thin filaments (actin). These filaments are organized into specific regions.
Step 2: Learn the definitions of the key regions within the sarcomere:
- The I band contains only thin filaments (actin).
- The A band contains both thick filaments (myosin) and overlapping thin filaments.
- The H zone is the central part of the A band that contains only thick filaments.
- The Z disc is the boundary between adjacent sarcomeres and anchors the thin filaments.
Step 3: Focus on the question, which asks for the region containing both thick and thin filaments. Based on the definitions, the A band is the region where thick and thin filaments overlap.
Step 4: Eliminate incorrect options:
- The I band contains only thin filaments, so it is not correct.
- The H zone contains only thick filaments, so it is not correct.
- The Z disc is a structural boundary and does not contain filaments in the overlapping arrangement, so it is not correct.
Step 5: Conclude that the correct answer is the A band, as it is the region of the sarcomere where both thick and thin filaments are present and overlap.
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