NEST2026BiologyNeural Control and Coordination
Events occurring during signal propagation in a chemical synapse are given below. P: Postsynaptic membrane potential changes. Q: Synaptic vesicle fuses with the presynaptic membrane. R: Action potential depolarizes the presynaptic terminal. S: Neurotransmitter binds to receptors on the postsynaptic membrane. T: Neurotransmitter is released into the synaptic cleft. The correct sequence of occurrence of these events is
Options
- AR, Q, T, S, P
- BQ, R, P, S, T
- CR, T, Q, P, S
- DQ, R, T, S, P
Correct answer
A. R, Q, T, S, P
Step-by-step solution
The sequence of events during signal propagation in a chemical synapse is as follows: First, an action potential arrives at the axon terminal and depolarizes the presynaptic terminal (R). This depolarization triggers the influx of calcium ions, causing synaptic vesicles to fuse with the presynaptic membrane (Q). Following fusion, the neurotransmitter is released into the synaptic cleft via exocytosis (T). The released neurotransmitter diffuses across the cleft and binds to specific receptors on the postsynaptic mem