Skeletal muscle 1

Question 1

What category of neurons controls skeletal muscle

Answer 1

Alpha motor neurons

Question 2

What is a single alpha motor neurone and the muscle fibres it innervates called

Answer 2

An motor unit

Question 3

How do you increase the force of muscle contraction

Answer 3

By recruiting more motor units

Question 4

Which units are recruited first and why

Answer 4

The small oxidative units that are more sensitive to a change in AP. Followed by larger glycolytic motor units

Question 5

Describe the pre-synaptic events of neuromuscular transmission

Answer 5

AP reaches the pre-synaptic terminal
AP causes depolarisation of voltage gated Ca2+ channels
Ca2+ causes vesicles with Ach to travel to cell membrane and release of Ach into the synaptic cleft occurs.
Ach diffuses across the cleft and bind to ACh receptors.

Question 6

Describe vesicle cycling

Answer 6

Vesicles are filled and form clusters at the active zone in presynaptic terminal.
After activation by Ca2+ vesicles are recycled.

Question 7

Describe post synaptic events

Answer 7

Ach binds to Ach receptor in post synaptic terminal. Ach binding causes the opening of non-specific ion channels. Influx of Na+, efflux of K+, depolarisation of motor end plate. Causes opening of voltage gated Na+ channels and Na+ influx, propagated AP in muscle fibre

Question 8

What is end plate potential

Answer 8

What occurs after initial influx of Na+ from ligand gated ion channels. It results in opening of voltage gated ion channels

Question 9

What is myasthenia gravis

Answer 9

An autoimmune disorder in which antibodies against the Ach receptors- fewer receptors less transmission