Muscle contraction

What is necessary for the myosin to release 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

What is a crossbridge?

• Where myosin binds to actin

• Where the calcium crosses into the cytoplasm

• Where calcium binds with troponin

• Where titin and myosin are connected

What does calcium do to the actin?

• Covers myosin binding sites

• Uncovers myosin binding sites

• Covers actin binding sites

• Uncovers actin binding sites

What is the name of the protein that covers the binding sites on actin?

• Myosin

• Titin

• Troponin

• Tropomyosin

What does the sarcoplasmic reticulum do?

• Stores sodium

• Stores ATP

• Releases sodium

• Stores calcium

What is the name of the place where a nerve meets a muscle fiber

• Nerve junction

• Neuromuscular junction

• Muscle junction

• Crossbridge

How does the sarcomere shorten (contract) ?

• The myosin filaments contract

• The actin filaments contract

• The myosin is pulled by the actin

• The actin is pulled by the myosin

When a muscle is in a contracted position, what is the relationship between actin filaments?

• They are on top of one another

• They are beside each other

• They are close to each other

• They are far apart from each other

When a muscle is relaxed and in a lengthened position, what is the relationship between actin filaments?

• They are on top of one another

• They are beside each other

• They are close to each other

• They are far apart from each other