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Cross-bridge formation that results in muscle contraction requires intracellular?
calcium ions. When muscle cells are stimulated, calcium ions bind to troponin, which allows the myosin heads to form cross-bridges with actin filaments, initiating muscle contraction.
What blocks the myosin binding sites on the actin molecule preventing cross bridge formation?
Tropomyosin covers the myosin binding sites on actin molecules, preventing cross bridge formation in a resting muscle. When calcium ions bind to troponin, it causes a structural change in tropomyosin, uncovering the myosin binding sites and allowing muscle contraction to occur.
When the sarcomere is at rest what is covering the active sites on actin?
When the sarcomere is at rest, the active sites on actin are covered by tropomyosin molecules. Tropomyosin blocks the myosin-binding sites on actin, preventing cross-bridge formation and muscle contraction.
Which molecules are involved with regulation of cross bridge attachment activity?
Molecules like calcium ions, ATP, tropomyosin, and troponin play crucial roles in regulating the activity of cross-bridge attachment between actin and myosin filaments in muscle contraction. The availability and binding of these molecules affect the conformational changes in the myosin heads that allow them to bind to actin and generate force.
What describes the events of contraction in excitation-contraction coupling?
cross bridge formation "Excitation-contraction coupling" connects muscle fiber excitation to the muscle fiber contraction (cross bridge formation). During contraction, myosin heads form cross bridges many times-with each cross bridge generating a small amount of tension in the muscle fiber.
What best describes the events of excitation in excitation-contraction coupling?
cross bridge formation "Excitation-contraction coupling" connects muscle fiber excitation to the muscle fiber contraction (cross bridge formation). During contraction, myosin heads form cross bridges many times-with each cross bridge generating a small amount of tension in the muscle fiber.
What is the actin status to begin cross bridge formation?
The actin binding sites are exposed
How are troponins I and T different?
cardiac troponin I tests measure only cardiac troponin; tests for cardiac troponin T may cross-react with troponin found in other muscles and give positive or increased results in the absence of heart damage.
What does calcium bind to priot to cross-bridging?
Actin changes shape.
When does cross bridge cycling end?
Cross bridge cycling ends when calcium is actively transported back into the sarcoplasmic reticulum, leading to a decrease in intracellular calcium levels. This causes the tropomyosin to block the binding sites on actin, preventing myosin from interacting and forming cross bridges. This relaxation of the muscle allows the muscle fibers to return to their resting state.
How would the loss of acetylcholinesterase from the motor end affect skeletal muscle?
Acetylcholine release is necessary for skeletal muscle contraction, because it serves as the first step in the process, enabling the subsequent cross-bridge formation. A muscle's ability to contract depends on the formation of cross-bridges between myosin & actin filaments. A drug that blocks acetylcholine release would interfere with this cross-bridge formation and prevent muscle contraction
What is the process of excitation contraction coupling?
Excitation-contraction coupling is the process in muscle cells where an action potential triggers the release of calcium ions from the sarcoplasmic reticulum. The calcium ions bind to troponin, causing a conformational change that allows myosin to bind to actin and initiate muscle contraction. When the action potential ceases, calcium ions are pumped back into the sarcoplasmic reticulum, leading to muscle relaxation.
