What accounts for the longest delay in neuronal signalling?

Question

BlackTom AI · Accepted Answer

The question asks which factor accounts for the longest delay in neuronal signalling.
Option a: Calcium entry into the synapse. While calcium entry is crucial for triggering vesicle fusion, the actual entry of Ca2+ through voltage-gated calcium channels is a relatively rapid process and does not by itself constitute the longest delay in transmission. It initiates the sequence, but the timing bottleneck lies downstream.
Option b: Potassium entry into the cell. Potassium movements largely contribute to repolarization and membrane potential dynamics, which are fast electrical events. They do not create the maximum pause in signalling compared to the synaptic transmission steps.
Option c: Sodium channel opening. Opening of sodium channels leads to rapid depolarization and action potential propagation along the axon. This is an electrical process with milliseconds or less of delay, not the chief source of delay in transmission.
Option d: Chemical transmission at the synapse. This option refers to the sequence after the action potential reaches the presynaptic terminal: vesicle docking and fusion, neurotransmitter release into the synaptic cleft, diffusion across the cleft, receptor binding on the postsynaptic membrane, and downstream signaling. Each of these stages adds time, and together they produce the characteristic synaptic delay that is typically longer than the purely electrical steps. This makes chemical synaptic transmission the main contributor to the longest delay in neuronal signalling.

What accounts for the longest delay in neuronal signalling?

View Explanation

Log in for full answers

Similar Questions

Which of the following explains why one-way synaptic transmission occurs?

Question at position 3 Select all the ways a neurotransmitter can exit the space between neurons.DiffusionReuptake/recyclingAxon travelEnzymes will digest the neurotransmitter.Immune cells will attack.

At a synapse between two neurons, the dendrites release the neurotransmitters.

Consider a neuron-neuron synapse. Match the description with the presynaptic or postsynaptic neuron. 1: Action potential travels away from the synapse via this neuron. 2: First in the chain of neurons. 3: Second in the chain of neurons. 4: Releases neurotransmitter.

The theory of quantal mechanism of neurotransmission was based on electrophysiology providing evidence for quantal activity in synaptic transmission combined with electron microscopy revealing vesicles near terminal boutons.

Which of the following is the correct sequence of events that occur during synaptic transmission?