The intersection of a muscle fibre and a nerve fibre is known as a neuromuscular junction. Neuromuscular transmission is the process by which information is transmitted from a motor nerve ending to a muscle fibre via a neuromuscular junction. Here let’s learn the steps involved in neuromuscular transmission with the help of a flowchart.
Table of Contents
- Neuromuscular Transmission
- Neuromuscular Transmission – Steps
- Neuromuscular Junction Flowchart
- Frequently Asked Questions
Neuromuscular Transmission
The definition of neuromuscular transmission is the information flow from the motor nerve ending to the muscle fibre via the neuromuscular junction. It is the process by which the motor nerve impulses start the contraction of the muscles.
The neuromuscular junction experiences a number of events throughout this process. Events include:
1. Acetylcholine release
2. Acetylcholine’s action
3. Increasing endplate potential
4. Potential for a miniature endplate development
5. Acetylcholine is destroyed
Neuromuscular Transmission – Steps
The five important steps in the process of neuromuscular transmission are as follows:
1. Acetylcholine release – When an action potential reaches an axon terminal, it opens voltage-gated calcium channels in the axon terminal’s membrane. The axon terminal receives calcium ions from the extracellular fluid. These force the synaptic vesicles to move and fuse with the presynaptic membrane and result in the bursting of the vesicles. Acetylcholine is now released from the ruptured vesicles. Acetylcholine diffuses through the presynaptic membrane and enters the synaptic cleft through the process of exocytosis.
2. Acetylcholine’s action – Acetylcholine molecules enter the synaptic cleft, where they interact with nicotinic receptors in the postsynaptic membrane to form the acetylcholine-receptor complex. By opening the ligand-gated sodium channels, it increases the postsynaptic membrane’s permeability for sodium. Now, sodium ions from ECF pass through these channels and enter the neuromuscular junction. And there, sodium ions change the electrical potential and create the endplate potential.
3. Increasing end plate potential – End plate potential is the shift in resting membrane potential that occurs at the neuromuscular junction as a result of an impulse. End plate potential is the result of a slight depolarization that happens when sodium ions enter the inside.
4. Potential for a miniature endplate development – Miniature endplate potential, which develops when a small amount of acetylcholine is released from the axon terminal, is a weak endplate potential in the neuromuscular junction. The muscle cannot develop an action potential as a result. The miniature endplate potentials are eventually added together to produce endplate potential, which results in an action potential in the muscle.
5. Acetylcholine is destroyed – Acetylcholinesterase enzyme quickly destroys the acetylcholine released into the synaptic cleft. The rapid breakdown of acetylcholine has some functional significance. It stops the muscle fibre from being excited repeatedly and enables the muscle to relax.
Also Check: MCQs on Muscle Contraction
Neuromuscular Junction Flowchart
Nerve impulse or action potential
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Opening of voltage-gated calcium channels
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Influx of calcium ions inside the cell increases
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Opening/rupture of vesicle and release of acetylcholine
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Acetylcholine comes to the synaptic cleft
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Acetylcholine binds with nicotinic receptors to form the acetylcholine-receptor complex
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Opening of ligand-gated sodium channels
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Influx of sodium ions inside the cell increases
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Development of endplate potential
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Generate muscle action potential
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Muscle contraction takes place
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