Skeletal Muscular Contraction Quiz

What is a motor unit?

• A motor neuron and all the muscle fibres it innervates

• A single muscle cell

• An electrical signal sent down the motor neuron

• The point where the motor neuron meets the muscle fibre

What is the role of acetylcholine (ACh) in muscle contraction?

• It detaches myosin from actin

• It forms cross-bridges with actin

• It releases calcium from the sarcoplasmic reticulum

• It binds to receptors on the sarcolemma, generating an action potential

Which muscle fibre type is most resistant to fatigue?

• Type I

• Type IIa

• Type IIx

• Type III

Which of the following is true about Type IIx muscle fibres?

• They are used in marathon running

• They produce low force

• They have low fatigue resistance

• They have a slow speed of contraction

What is the function of the neuromuscular junction?

• To release calcium from the sarcoplasmic reticulum

• To serve as the point where the motor neuron meets the muscle fibre

• To transmit impulses from the CNS to muscle fibres

• To generate ATP for muscle contraction

What is the All-or-None Law?

• Muscles recruit more motor units for greater force

• If a stimulus exceeds the threshold, all muscle fibres in the motor unit contract fully

• Smaller motor units are recruited first

• Increased frequency can lead to summation and tetanus

Which activity is an example of using Type IIa muscle fibres?

• Swimming

• Weightlifting

• 400m sprint

• Marathon running

What is the first step in the process of skeletal muscle contraction?

• Power stroke

• Cross-bridge formation

• Calcium release

• Stimulus from the brain

What is the Henneman’s Size Principle?

• Smaller (slow-twitch) motor units are recruited first, followed by larger (fast-twitch) units

• All muscle fibres in the motor unit contract fully if a stimulus exceeds the threshold

• Increased frequency can lead to summation and tetanus

• Muscles recruit more motor units for greater force

Which of the following best describes Type I muscle fibres?

• They are fast-twitch and fatigue quickly

• They are slow-twitch and have high endurance

• They are used primarily for explosive movements

• They have a high glycolytic capacity