The functional unit of contractile system of a striated muscle isa) Sarcomere b) Z-band c) Cross bridge d) Myofibril Correct answer is option 'A'. Can you explain this answer?

Question

The functional unit of contractile system of a striated muscle isa)                                  Sarcomere                               b)                                  Z-band                               c)                                  Cross bridge                               d)                                  Myofibril                               Correct answer is option 'A'. Can you explain this answer?

Answer

The portion of the myofibril between two successive Z lines is considered as the functional unit of contraction and is called 'SARCOMERE' ...

SARCOMERE = ONE A BAND + TWO HALF I BAND

THE LENGTH OF SARCOMERE IS 2.5 um :)

Answer

The functional unit of the contractile system of a striated muscle is:A: SarcomereExplanation:- Sarcomere: The sarcomere is the basic structural and functional unit of striated muscle fibers, responsible for their contraction and relaxation. It is a repeating unit along the length of a myofibril, consisting of overlapping thick (myosin) and thin (actin) filaments, and delimited by Z-bands. - Contains actin and myosin filaments, which are responsible for muscle contraction - Organized in a highly ordered manner, allowing for the sliding filament mechanism to occur during muscle contraction - Length changes during contraction, leading to shortening of the muscle fiber and generation of force- Z-band: These are not the functional units of contraction, but rather, they serve as structural anchors for the thin filaments and define the lateral boundaries of the sarcomere. They are responsible for maintaining the organized arrangement of the sarcomere.- Cross bridge: This term refers to the interaction between actin and myosin filaments during muscle contraction, when the myosin head binds to actin to form a cross bridge. Although cross bridges are crucial for muscle contraction, they are not considered the functional unit of the contractile system.- Myofibril: Myofibrils are long, cylindrical structures found within muscle fibers, containing repeating sarcomeres. While myofibrils play a crucial role in muscle contraction, they are not the functional unit of the contractile system. Instead, they are composed of multiple sarcomeres, which are the actual functional units responsible for muscle contraction.

Answer

The functional unit of the contractile system of a striated muscle is:A: SarcomereExplanation:- Sarcomere: The sarcomere is the basic structural and functional unit of striated muscle fibers, responsible for their contraction and relaxation. It is a repeating unit along the length of a myofibril, consisting of overlapping thick (myosin) and thin (actin) filaments, and delimited by Z-bands. - Contains actin and myosin filaments, which are responsible for muscle contraction - Organized in a highly ordered manner, allowing for the sliding filament mechanism to occur during muscle contraction - Length changes during contraction, leading to shortening of the muscle fiber and generation of force- Z-band: These are not the functional units of contraction, but rather, they serve as structural anchors for the thin filaments and define the lateral boundaries of the sarcomere. They are responsible for maintaining the organized arrangement of the sarcomere.- Cross bridge: This term refers to the interaction between actin and myosin filaments during muscle contraction, when the myosin head binds to actin to form a cross bridge. Although cross bridges are crucial for muscle contraction, they are not considered the functional unit of the contractile system.- Myofibril: Myofibrils are long, cylindrical structures found within muscle fibers, containing repeating sarcomeres. While myofibrils play a crucial role in muscle contraction, they are not the functional unit of the contractile system. Instead, they are composed of multiple sarcomeres, which are the actual functional units responsible for muscle contraction.

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The functional unit of contractile system in striated muscle is[1998]

The functional unit of contractile system in a striated muscle is

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Assertion: The portion of the myofibril between two successive Z lines is considered as the functional unit of contraction called sarcomere.Reason: During contraction, I bands get reduced whereas A bands retain the length, thereby causing shortening of the sarcomere.

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