PHYSIOLOGY
MUSCLE CONTRACTION
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
Troponin moves, revealing binding sites for myosin heads
|
|
|
Tropomyosin moves, revealing binding sites for myosin heads
|
|
|
Calcium moves, revealing binding sites for myosin heads
|
|
|
Myosin moves, binding to calcium
|
Detailed explanation-1: -(2) Calcium binds to troponin C, which induces a conformational change in the troponin complex. This causes tropomyosin to move deeper into the actin groove, revealing the myosin-binding sites.
Detailed explanation-2: -Key Points. Tropomyosin covers the actin binding sites, preventing myosin from forming cross-bridges while in a resting state. When calcium binds to troponin, the troponin changes shape, removing tropomyosin from the binding sites.
Detailed explanation-3: -The myosin binding sites on actin sites are exposed after calcium enters the sarcoplasm and activates the troponin-tropomyosin complex to shift. The latching of myosin heads docking onto actin-binding sites begins the “cross bridge cycle” a process that continues as long as calcium and ATP are present.