Muscle Innervation/ Spinal Reflexes

Question 1

Motor Unit

Answer 1

Alpha motor neuron and innervated extrafusal fibers

Question 2

Type I Motor Unit

Answer 2

Slow-twitch fibers; low tension; fatigue-resistant; aerobic; innervated by relatively small motor neuron and axon

Question 3

Type IIa Motor Unit

Answer 3

Fast; relatively fatigue-resistant; large tension; some aerobic capacity; innervated by relatively large motor neuron and axon

Question 4

Type IIb Motor Unit

Answer 4

Fast; fatigue-susceptible; large tension; anaerobic; innervated by relatively large motor neuron and axon

Question 5

Two Crucial Factors Controlling Contraction

Answer 5

1. The firing rates of the motor neurons

2. The number of motor units recruited