U1 L8: Nervous Control of Muscles

What is the role of the brain in the neural control of muscles?

• To relax the muscles

• To send electrical nervous messages to the muscles

• To increase muscle size

• To decrease muscle tension

What is the first stage in the nervous control of muscle action?

• Message passes into motor neurons

• Brain initiates message

• Message branches off to muscle fibers

• Nervous impulse travels across synaptic cleft

What is required for a muscle contraction to occur?

• A weak nerve impulse

• A strong enough nerve impulse

• No nerve impulse

• Continuous relaxation

What is the function of a motor neuron in a motor unit?

• To relax the muscle fibers

• To stimulate the muscle fibers

• To inhibit the muscle fibers

• To detach the muscle fibers

Which type of motor units are recruited first at low muscle forces?

• Large motor units

• Fast-twitch motor units

• Small motor units

• Slow-twitch motor units

What is a characteristic of large motor units?

• Slow contracting

• Rapidly fatigable

• Fatigue resistant

• Used for prolonged activities

Which of the following is NOT a use for small motor units?

• Walking

• Posture control

• Jumping

• Prolonged activities

What is the effect of activating more motor units?

• Less force is generated

• More force is generated

• No change in force

• Decrease in muscle size