10. Fast and Slow Muscle, Muscle Disorders

Question 1

What is a motor unit?

Answer 1

Motor neuron and all the muscle fibres it innervates

Question 2

What is electromyography?

Answer 2

Electrical activity of skeletal muscle is recorded using electrodes in or near the muscle

Question 3

Describe the characteristics of fast muscle (2b)

Answer 3

Rapid, intense, phasic, easily fatigued
Anaerobic
White
Longer motorneurons

Question 4

Describe the characteristics of slow muscle (Type 1)

Answer 4

Slow, sustained, tonic, fatigue resistant
Aerobic
Red
Smaller motorneurons
Recruited first in moderate contractions

Question 5

What is denervation?

Answer 5

Lesion of motor nerves to skeletal muscle causes flaccid paralysis
Fascilations
Nerve regeneration restores function
Failure to regenerate results in type 1 and 2 fibre atrophy

Question 6

What are fascilations?

Answer 6

Visible twitching caused by the release of ACh from degenerating motor neurons

Question 7

What causes atrophy?

Answer 7

Peripheral neuropathy, disuse, Parkinson’s

Duchenne muscular dystrophy, ageing

Question 8

What is neuropathy a disease of?

Answer 8

Motor neurons

Question 9

What is junctionopathy a disease of?

Answer 9

Neuromuscular junction

Question 10

What is myopathy a disease of?

Answer 10

Muscle

Question 11

What is sarcopaenia?

Answer 11

Loss of muscle size and strength with age