Motor Units

Question 1

Motor unit

Answer 1

Consist of a motor neurone and a number of muscle fibres

Question 2

Neurone

Answer 2

Type of nerve cell

Question 3

Axon

Answer 3

Carries the action potential from the cell to the neuromuscular junction

Question 4

Neuromuscular junction

Answer 4

Where the motor neurone communicates with the muscle fibres across the synapse

Question 5

Synapse

Answer 5

The space between the neuromuscular junction and the skeletal muscle

Question 6

Motor end plate

Answer 6

Area of muscle fibre which establishes synaptic contact with the motor neurone

Question 7

Resting potential

Answer 7

Where there is a lower charge inside the neurone than outside the neurone

Question 8

Action potential

Answer 8

The electrical impulse carried down the axon

Question 9

Neurotransmitter

Answer 9

Chemical transmitters which diffuse across a synapse binding to receptors to initiate muscular contraction

Question 10

Acetyl choline

Answer 10

The neurotransmitter released at the neuromuscular junction and diffuses across the synapse

Question 11

All or nothing law

Answer 11

If the AP threshold is reached, all the muscle fibres in the motor unit will contract and if the AP threshold is not reached then none of the muscle fibres contract

Question 12

Summary of motor units

Answer 12

The central nervous system sends an electrical impulse to the motor neurone (specialised cells). The motor neurone transmits a nerve impulse. An action potential holds the nerve impulse and is a wave of electrical charge down the axon to the motor end plates. This is called the neuromuscular junction the small gap between the motor end plate and the muscle fibres is called the synaptic cleft. Then the All or None law happens