PHYSIOLOGY
MUSCLE CONTRACTION
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
Why is calcium absolutely essential for muscle contraction?
|
|
Calcium makes bones stronger, which means muscles also get stronger.
|
|
|
Calcium binds to troponin, simply exposing the myosin binding site for actin.
|
|
|
Calcium inhibits muscle contraction because it depolarizes the cell.
|
|
|
Calcium is needed in order for ATP to attach to myosin heads, which causes contraction.
|
Explanation:
Detailed explanation-1: -Once the myosin-binding sites are exposed, and if sufficient ATP is present, myosin binds to actin to begin cross-bridge cycling. Then the sarcomere shortens and the muscle contracts. In the absence of calcium, this binding does not occur, so the presence of free calcium is an important regulator of muscle contraction.
Detailed explanation-2: -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. Thin filaments without troponin support contraction irrespective of calcium concentration.
There is 1 question to complete.