Question

Calcium is important in skeletal muscle contraction because it

• A. prevents the formation of bonds between the myosin cross bridges and the actin filament
• B. binds to troponin to remove the masking of active sites on actin for myosin.
• C. detaches the myosin head from the actin filament.
• D. activates the myosin ATPase by binding to it

Answer 1

The Correct Option is B

Muscle tension can be produced without a change in the length of the muscle, for example, while lifting a heavy book or a dumbbell at the same position, proving that muscle contraction does not necessarily equate to muscle shortening. An impulse that leaves the motor endplate or neuromuscular junction and travels up the axon to start a muscle contraction. As a result, acetylcholine is produced into the synaptic cleft, and the sarcolemma experiences the resulting action potential.
The emergence of this action potential causes the sarcoplasmic reticulum to discharge calcium ions into the sarcoplasm. Actin sites are activated as a result of the sarcoplasm's increased calcium ion concentration. Actin filaments covered in troponin are removed by calcium ions, which bind to the troponin. As a result, active action sites are revealed, allowing myosin heads to connect to this site. Myosin heads pull the actin filament after a muscle contraction, releasing ADP and inorganic phosphate. Myosin is damaged, and ATP molecules bind and detach it from the cross Bridge. Calcium ions control skeletal muscle contraction. These calcium ions attach to the protein complex and take away the active sites' masking. As a result, myosin's active binding sites are made visible.