Motor Unit Flashcards
What is a motor unit?
- Muscle Fibres
- Motor neurones
What is the purpose of dendrites?
They collect signals/impulses sent from the central nervous system
What does the axon do?
It processes the signal and conducts impulse to the neuromuscular junction
What is an action potential?
The change in electrical potential along the membranes of nerve cells which helps to conduct nerve impulses
What is a neurotransmitter?
A chemical which is secreted into the synaptic cleft to allow the action potential to cross the neuromuscular junction
What neurotransmitter is used in the motor unit?
Acetylcholine (ACh)
What is the synaptic cleft?
The gap between the end of axon and motor neurone end plate - which the electrical impulse must cross in order to stimulate the muscle fibres
What is the ALL or NONE LAW?
If the action potential reaches threshold then all muscle fibres (stimulated) will contract with maximum force. If the AP doesn’t reach threshold then none of the muscles will contract
Describe the nervous stimulation of a motor unit?
The dendrites collect the signal given by the central nervous system (CNS). Impulse starts in the cell body (nucleus) of motor neurone through action potential which is formed from depolarisation (adding Na+ ions).
AP travels down the axon.
Once it reaches the neuromuscular junction acetylcholine is secreted into the synaptic cleft.
Impulse crosses synaptic cleft to muscle fibres and if the impulse in above threshold all muscle fibres will contract (All or None fashion)
What is the neuromuscular junction?
The point where the axons motor end plate meets the muscle fibre
