Motor units

Question 1

Lower motor neurons

Answer 1

Alpha neurons

• Large cell body
• extensive dendritic tree
• large axon- up to 1+ m in length
• myelinated with schwann cells
• rapid conduction velocity

Question 2

motor unit made up of

Answer 2

Cell body
its axon
all the muscle fibers that axon innervates- motor neuron pool

Question 3

S-Slow motor unit

Answer 3

Small peak force

slow to fatigue

Question 4

FR- fast fatigue resistant

Answer 4

Fast rate of force increase during twitch
-moderate peak force
will stop producing force after many seconds

Question 5

FF- fast, fatiguable

Answer 5

Large peak force

stops producing force within seconds

Question 6

Recruitment

Answer 6

previous silent motor unit

• stronger inputs lead to recruitment of more powerful motor units
• Size principle

Question 7

Rate-coding

Answer 7

already firing motor unit

• increase firing rate
• partially fused force output
• Fully fused at highest firing rate