Concept explainers
(1)
To draw: A cross-section diagram that shows in the H zone.
Introduction: Myofilaments within the myofibrils are organized in a continuous manner with cylindrical units called sarcomeres. Inside the skeletal muscle fibers, there are several repeating sarcomeres arranged within a section of a myofibril. Overlapping of thick and thin filaments constitutes each sarcomere.
(1)
Explanation of Solution
Pictorial representation: Fig.1 represents the H zone though a cross-section of muscle fiber.
Fig.1: H zone
The H zone is the central portion of the A band that is present only in the resting sarcomere. The H zone region does not have overlapping thin filament. It only has thick filament.
(2)
To draw: A cross-section diagram that shows in the I band.
(2)
Explanation of Solution
Pictorial representation: Fig.1 represents the I band though a cross-section of muscle fiber.
Fig.1: I zone
The I band is the only region that contains thin filament and extends from both the directions of Z disk. At the regions of maximal shortening, the thin filaments of the muscle fiber are pulled parallel along the thick filaments. This leads to decrease of the I bands.
(3)
To draw: A cross-section diagram that shows at the M line.
(3)
Explanation of Solution
Pictorial representation: Fig.1 represents the M line though a cross-section of muscle fiber.
Fig.1: M line
The M line is the narrow, dark band in the center region of the H zone known as the M line that corresponds to proteins linked together at the central region of the adjacent thick filament.
(4)
To draw: A cross-section diagram that shows in the Z line.
(4)
Explanation of Solution
Pictorial representation: Fig.1 represents the Z line though a cross-section of muscle fiber.
Fig.1: Z line
Sarcomeres are composed of thin and thick overlapping filaments. They are delineated by Z disks on both ends. These disks are composed of specialized proteins that are perpendicular to myofilaments and function as an anchor for the thin filament.
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Chapter 9 Solutions
Vander's Human Physiology
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