Muscle Contraction and Motor Units

Which of the following is the smallest skeletal muscle in the human body?

• Sartorius

• Gluteus Maximus

• Stapedius

• Rectus Femoris

What is a fundamental principle of how skeletal muscles move bones?

• Muscles always push

• Muscles can both push and pull

• Muscles always pull

• Muscles primarily extend

What is the term for muscles that are mainly responsible for producing a specific movement?

• Antagonists

• Synergists

• Fixators

• Prime Movers

What defines a motor unit?

• A single muscle fiber and its associated nerve

• A group of muscle fibers that all get their signals from the same, single motor neuron

• All the muscles in a specific limb

• The entire muscle organ

What occurs during the latent period of a muscle twitch?

• Myosin heads bind and pull on actin

• Calcium ions are pumped back into the sarcoplasmic reticulum

• The muscle fiber is stimulated, but no force is produced yet

• The muscle fiber fully relaxes

How does the brain increase the force generated by a muscle?

• By decreasing the frequency of motor neuron firing.

• By increasing the frequency of motor neuron firing.

• By decreasing the number of motor units activated.

• By increasing the relaxation period between twitches.

What is the term for a sustained muscle contraction where individual twitches blend together to reach maximum tension?

• Temporal summation

• Tetanus

• Muscle fatigue

• Recruitment

What is the primary reason vigorous muscle activity cannot be maintained indefinitely?

• Depletion of calcium ions.

• Finite supply of ATP.

• Accumulation of lactic acid.

• Damage to myosin heads.

How does the body increase the overall strength of a muscle contraction beyond increasing the firing frequency of individual motor units?

• By decreasing the number of active motor units.

• By activating motor units with fewer muscle fibers.

• By recruiting more motor units.

• By reducing the amount of calcium released.

Which type of muscle contraction involves the muscle changing length while generating force?

• Isometric

• Isotonic

• Tetanic

• Temporal