What is a motor unit ad explain neuromuscular junctions?
Answers
A neuromuscular junction (or myoneural junction) is a chemical synapse formed by the contact between a motor neuron and a muscle fiber. It is at the neuromuscular junction that a motor neuron is able to transmit a signal to the muscle fiber, causing muscle contraction.
Answer is for Class 11 Biology Student.
Motor Unit :
A motor neuron delivers stimulus that ultimately causes a muscle fibre to contract.
A motor neuron plus all skeletal muscle fibres it stimulates; together constitute a motor unit.
Note:
A single neuron makes contact with an average of 150 muscle fibres. This means activation of one neuron causes simultaneous contraction of 150 muscle fibres.
All muscle fibres of a motor unit contract and relax together.
Neuro- Muscular Junction:
Synapse formed between a motor neuron and skeletal muscle fibre is called neuro-muscular junction.
Axon terminals of neuron release acetylcholine as neurotransmitter in the synaptic region.
The region of muscle fibre plasma membrane that is adjacent to axon terminals is called motor end plate. It contains acetylcholine receptors.
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