Practice Quiz on Muscles and Muscle Contraction

The _________ are attached to the Z-lines?

• myosin filaments (thick filaments)

• actin filaments (thin Filaments)

• myosin cross-bridges

• troponin proteins

• tropomyosin proteins

What is the contractile unit that extends from Z-line to Z-line?

• Sarcomere

• T Tubule

• Sarcoplasmic reticulum

• Fascicle

This structure attaches to the actin filament to form the cross-bridge.

• Troponin

• Tropomyosin

• Myosin

• Calcium

What does calcium attach to in a muscle contraction?

• Myosin

• Tropomyosin

• Troponin

• Actin

The H zone in the sarcomere changes size during a muscle contraction.

• True

• False

What is released from the sarcoplasmic reticulum when a muscle cell is stimulated?

• Farts

• Myosin

• Calcium

• ATP

What is the name of the neurotransmitter released at a neuromuscular junction?

• Calcium

• Acetylcholine

• Dopamine

• Troponin

What is needed for the myosin to break the cross-bridge attachment from the actin?

• ATP

• Calcium

• ADP

• Sodium

What does the myosin do to the actin?

• Nothing

• Pushes on it

• Pulls on it

• Breaks it into pieces

Why is calcium so important to actin in muscle contraction?

• Calcium covers the myosin binding sites on the actin.

• Calcium uncovers the myosin binding sites on the actin.

• Calcium binds to the troponin, which then pulls the tropomyosin off of the myosin binding sites on the actin.

• Calcium binds to the tropomyosin, which then pulls the troponin off of the myosin binding sites on the actin.