Normally, Acetylcholine (ACh) binds to α-subunit of Acetylcholine Receptor (AChR) at postsynaptic junction. Which ion is responsible for transmission of impulse from postsynaptic junction to nerve fibers?
- Chloride (Cl)
- Calcium (Ca)
- Sodium (Na)
- Magnesium (Mg)
Presynaptic Fibre (Acetylcholine) ⇒ Synaptic Cleft ⇒ Postsynaptic Fibre (Acetylcholine Receptors)
Calcium ions bind to synaptic vesicles, triggering vesicle fusion with the cell membrane and subsequent neurotransmitter release from the motor neuron into the synaptic cleft. Motor neurons release acetylcholine (ACh) neurotransmitter, which diffuses across the synaptic cleft and binds to nicotinic acetylcholine ionotropic receptors (nAChRs) on the cell membrane of the muscle fiber. The binding of ACh to the receptor can depolarize the muscle fiber, results in muscle contraction.