Understanding Muscle Contraction Mechanism (Wellcome video)s

What structure attaches skeletal muscles to bones?

• Ligaments

• Tendons

• Cartilage

• Fascia

What are skeletal muscles primarily composed of?

• Myelin sheaths

• Muscle fibres

• Adipose tissue

• Bone marrow

Which structure provides an attachment for myosin filaments in a sarcomere?

• Z line

• M line

• A band

• I band

What is the role of tropomyosin in muscle contraction?

• It binds calcium ions

• It blocks the myosin binding site on actin

• It hydrolyses ATP

• It forms cross-bridges with actin

What triggers the release of calcium ions from the sarcoplasmic reticulum?

• Muscle relaxation

• Action potential

• ATP depletion

• Myosin head detachment

What happens when calcium ions bind to troponin?

• Tropomyosin blocks the myosin binding site

• Myosin heads detach from actin

• Tropomyosin moves, exposing the myosin binding site

• ATP is synthesised

What is the function of ATP in muscle contraction?

• It provides energy for myosin head detachment

• It blocks calcium ion channels

• It binds to actin filaments

• It forms the Z line

Which band of the myofibril contains only actin filaments?

• A band

• H band

• I band

• M band

What happens to calcium ions after the action potential is passed?

• They remain in the myofibrils

• They are pumped back into the sarcoplasmic reticulum

• They bind permanently to troponin

• They are converted into ATP

During muscle contraction, what happens to the actin and myosin filaments?

• They shorten

• They lengthen

• They slide past each other

• They dissolve