Stimulation Of A Motor Unit Flashcards
What is a motor unit
A motor neurone plus all the muscle fibres it initiates
What is a neurone
A type of nerve cell
What is an axon
Carries the action potential (AP) from the cell body to the neuromuscular junction
What is the neuromuscular junction
Where the motor neurone communicates with the muscle fibres across the synapse
What is a synapse
The space between the neuromuscular junction and the skeletal muscle
What is the motor end plate
Area of muscle fibre which establishes synaptic contact with the motor neurone
What is resting potential
Where there is a lower charge inside the neurone than outside the neurone
What is action potential
The electrical impulse carried down the axon
What is a neurotransmitter
A chemical transmitter that diffuses across a synapse binding to receptors to initiate muscular contraction
What is acetylcholine (ACh)
The neurotransmitter released at the neuromuscular junction and diffuses across the synapse
What is the all or nothing law
If the action potential is reached, all the muscle fibres in the motor unit are initiated. If the action potential threshold is not reached then none of the muscle fibres are initiated
Describe the stimulation of a motor unit
MAN-SAYS-ALL
M = Motor neurone + muscle fibre
A = Action potential travels down axon
N = Neuromuscular junction
S = Synaptic cleft
A = Acetylcholine (neurotransmitter)
Y = Why?
S = Signal can pass into muscle fibres
ALL = If signal is high enough, ALL muscle fibres contract. If it is not high enough, NO muscle fibres contract
