Sliding Filament Model

___are thin filaments.

• troponin

• tropomyosin

• actin

• myosin

___are thick filaments.

• actin

• myosin

• troponin

• tropomyosin

Calcium binds to ___of the troponin-tropomyosin complex.

• troponin

• tropomyosin

• actin

• myosin

A ___extends from one Z disc to another Z disc.

• Sarcolemma

• Neuromuscular junction

• Sarcomere

• A-band

What is a crossbridge?

• Where myosin binds to actin
• Where the calcium crosses into the cytoplasm
• Where calcium binds with troponin
• None of the answers are correct.

The sliding filament theory of muscle contraction says

• Actin and myosin filaments condense, thus causing the filament to shorten which in turn shortens the muscle

• Myosin rotates and wraps actin around it making the muscle shorter

• Friction is reduced between thin and thick filaments causing the thick filaments to move inside the thin

• Actin filaments slide over myosin filaments, making the muscle shorter

Which number represents the sarcomere?

• 1

• 2

• 3

• 4

Which number represents the actin filament?

• 1

• 2

• 3

• 4

Which number represents the myosin filament?

• 1

• 2

• 3

• 4

What happens to the muscle when the concentration of calcium ions decreases?

• The muscle contracts more forcefully.

• The muscle relaxes.

• The muscle becomes paralyzed.

• The muscle begins to twitch uncontrollably.