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In short, the basic contraction unit of the muscle is the sarcomere. Many sarcomeres work serially and in parallel to acheive the full contraction ability of the muscle. The sarcomere is made up of many filaments of Actin and Myosin, two types of protein based filaments that reach out towards each other from opposing sides of the sarcomere. When the muscle is at rest, the Actin and myosin filaments overlap each other the least. In order for the muscle to contract, the filaments from the opposing sides slide over each other thus pulling both walls of the sarcomere towards each other, with them. When the muscle is fully contacted, the filaments overlap each other the most. The sliding motion is activated by calcium that floods the sarcomeres (at the end of a process that is triggered by a command from a motor nerve). The calcium reveals sites on the Actin filaments at which molecular 'whips' extending from the Myosin filaments, can throw themselves, attach, pull, and leave, using the muscle's energy reserves in the process. Each molecular whip works at its own time (much like cylinders in an internal combustion engine), so that in any given time, contact between the filaments is being made by some of the whips.
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What myofilament does the pulling?
The myosin myofilament pulls on the actin myofilament during muscle contraction. This interaction, known as the sliding filament theory, results in the shortening of the sarcomere and muscle contraction.
Physical evidence that supports the sliding filament theory of muscle contraction includes?
decreased width of the H band during contraction
What is the model that best describes the contraction of the muscle called?
The sliding filament theory is the model that best describes muscle contraction. It explains how actin and myosin filaments slide past each other, resulting in muscle fiber shortening and contraction. This theory is widely accepted in the field of muscle physiology.
What filament is responsible for the pulling and what filament is pulled in the sliding filament theory?
In the sliding filament theory of muscle contraction, the thin filament (actin) slides over the thick filament (myosin). Myosin is responsible for pulling the actin filaments towards the center of the sarcomere during muscle contraction.
What is a cross bridge in a muscle contraction?
A cross bridge in muscle contraction refers to the temporary connection formed between the myosin heads of thick filaments and the actin filaments of thin filaments within a muscle fiber. This interaction occurs during the contraction cycle when calcium ions bind to troponin, causing tropomyosin to shift and expose binding sites on actin. The myosin heads then attach to these sites, pulling the actin filaments toward the center of the sarcomere, which leads to muscle shortening and contraction. This process is a key component of the sliding filament theory of muscle contraction.
What width remains constant during muscle contraction?
During muscle contraction, the width of the A band remains constant. The A band corresponds to the length of the thick filaments (myosin) and does not change in size during contraction. In contrast, the I band (which contains only thin filaments or actin) shortens as the muscle contracts. This consistent width of the A band reflects the sliding filament theory of muscle contraction, where the filaments slide past each other without changing their lengths.
In isometric contraction how does the muscle stay the same length when the sarcomeres are shortening according to the sliding filament theory?
Dear freind! there is not any filamnet sliding in isometric contraction and so there is no work...
What is the term that refers to the theory of rapidly lengthening a muscle followed by an immediate concentric contraction?
This is known as plyometric stretching, a form of dynamic stretching that combines rapid lengthening of a muscle with an immediate concentric contraction to improve power and explosiveness in movements.
What enzymes do myosin heads have?
Myosin heads contain ATPase enzymes, which hydrolyze ATP to provide energy for muscle contraction. This energy is used to power the movement of myosin heads along actin filaments during the sliding filament theory of muscle contraction.
Who proposed the sliding filament theory?
it was a collaboration between Jean Hanson and Hugh Huxley
What is the function sarcomere?
A sarcomere is the basic contractile unit of muscle fibers, crucial for muscle contraction. It is composed of overlapping thick (myosin) and thin (actin) filaments organized in a specific arrangement, allowing for shortening during contraction. Sarcomeres are aligned end-to-end along myofibrils, and their coordinated contraction leads to muscle movement. The sliding filament theory explains how these filaments slide past each other, facilitating muscle shortening and force generation.
When muscle fibers are stimulated to contract what is occur ing?
When muscle fibers are stimulated to contract, an electrical impulse travels along the muscle cell membrane, leading to the release of calcium ions from the sarcoplasmic reticulum. This release of calcium triggers the interaction between actin and myosin filaments, the proteins responsible for muscle contraction. The myosin heads attach to actin and pull, causing the muscle fiber to shorten and generate force. This process is known as the sliding filament theory of muscle contraction.
