Textbook Question
Mark the following statements as true or false. If a statement is false, correct it to make a true statement.
The plasma membrane of a muscle cell is called the sarcoplasmic reticulum.
738
views
9. Muscle Tissue
Introduction to Muscles and Muscle Tissue
Problem 4
Textbook Question
Match the following terms with the correct definition.
____Z-disc
____Sarcomere
____A band
____H zone
____I band
____M line
a. The dark band containing the entire length of the thick filament
b. The band of proteins in the middle of the H zone
c. The boundary between sarcomeres
d. The functional unit of contraction
e. The middle region of the A band containing only thick filaments
f. The light band containing only thin filaments
Verified step by step guidance1
Step 1: Understand the terms and their roles in muscle anatomy. These terms are related to the structure of a sarcomere, which is the functional unit of a muscle fiber. A sarcomere is composed of repeating units of thick and thin filaments, and the arrangement of these filaments creates distinct bands and zones.
Step 2: Match the term 'Z-disc' with its definition. The Z-disc (or Z-line) is the boundary between sarcomeres, where thin filaments are anchored. This corresponds to definition (c).
Step 3: Match the term 'Sarcomere' with its definition. The sarcomere is the functional unit of contraction in a muscle fiber, as it is the smallest unit capable of contracting. This corresponds to definition (d).
Step 4: Match the term 'A band' with its definition. The A band is the dark band that contains the entire length of the thick filament, including regions where thick and thin filaments overlap. This corresponds to definition (a).
Step 5: Continue matching the remaining terms: 'H zone' is the middle region of the A band containing only thick filaments (e), 'I band' is the light band containing only thin filaments (f), and 'M line' is the band of proteins in the middle of the H zone (b).
Verified video answer for a similar problem:This video solution was recommended by our tutors as helpful for the problem above
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Z-disc
The Z-disc, or Z-line, is a structural component of a sarcomere, which serves as the boundary between adjacent sarcomeres in a muscle fiber. It anchors the thin filaments (actin) and plays a crucial role in the contraction process by maintaining the alignment of the sarcomere during muscle contraction and relaxation.
Recommended video:
Guided course
6:01
Structure of the Sarcomere: Bands, Zones, Discs & Lines
Sarcomere
The sarcomere is the fundamental unit of muscle contraction, defined as the segment between two Z-discs. It contains overlapping thick (myosin) and thin (actin) filaments, and its contraction is responsible for the shortening of muscle fibers, enabling movement. Understanding the structure of the sarcomere is essential for grasping how muscles function.
Recommended video:
Guided course
7:18Proteins of the Sarcomere
A band
The A band is the dark region of the sarcomere that contains the entire length of the thick filaments (myosin) and overlaps with the thin filaments (actin). This band is crucial for muscle contraction, as it represents the area where the force is generated during the sliding filament mechanism. The A band remains constant in length during contraction, while the I band and H zone change.
Recommended video:
Guided course
6:01Structure of the Sarcomere: Bands, Zones, Discs & Lines
Related Videos
Related Practice