Muscle Contraction Quiz

What triggers the release of acetylcholine into the synapse?

• Action potential

• Sarcoplasmic reticulum

• ATP

• Calcium ions

What causes the sarcoplasmic reticulum to release stores of calcium ions?

• Acetylcholine

• Depolarization

• T tubules

• ATP hydrolysis

What is the role of calcium ions in cross-bridge formation?

• Moving the actin filaments towards the centre of the sarcomere

• Binding to troponin and exposing the binding sites for the myosin heads

• Swiveling the myosin heads

• Breaking the cross-bridge between actin and myosin

What causes the myosin heads to change position and swivel?

• Depolarisation

• Acetylcholine release

• Calcium ions binding to troponin

• ATP hydrolysis

Which parts of the sarcomere move during the sliding filament theory? (more than one answer)

• The thin filaments

• The thick filaments

• The z lines

• The m line

What is the role of Na+ ions in initiating muscular contractions?

• Breaking the cross-bridge between actin and myosin

• Initiating depolarization within the sarcolemma

• Causing the myosin heads to change position and swivel

• Exposing the binding sites for the myosin heads

What is the result of the repeated reorientation of the myosin heads?

• The muscle fibres contract

• The sarcomere shortens

• The actin filaments form a cross-bridge with myosin

• The sarcoplasmic reticulum releases calcium ions

What is the function of ATP in the sliding mechanism of actin and myosin?

• Breaking the cross-bridge between actin and myosin

• Exposing the binding sites for the myosin heads

• Causing the myosin heads to change position and swivel

• Moving the actin filaments towards the centre of the sarcomere

What is the role of troponin and tropomyosin in muscle contraction?

• Covering the binding sites for the myosin heads

• Exposing the binding sites for the myosin heads

• Moving the actin filaments towards the centre of the sarcomere

• Causing the myosin heads to change position and swivel

What is required to make a muscle cell relax?

• ATP

• calcium

• myosin binding sites blocked

• Ach