PHYSIOLOGY
SYNAPTIC PHYSIOLOGY
|
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: -Upon binding calcium, troponin moves tropomyosin away from the myosin-binding sites on actin (bottom), effectively unblocking it.
Detailed explanation-3: -An action potential generated by a motor neuron propagates on the muscle cell surface, activates voltage-gated calcium channels and allows calcium flow into the muscle cell.
Detailed explanation-4: -Troponin plays a central role in the calcium-regulation of muscle contraction: Troponin is the sole calcium-binding component of thin filaments (actin-tropomyosin-troponin complex) of striated muscles.
Detailed explanation-5: -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.