Question

Communication by the nervous system depends on the flow of information through chains of neurons that are functionally connected by synapses. The most common synapse in the human body is the chemical synapse.

1. Define chemical synapse. 3 points
2. Describe the chain of events that occur at a chemical synapse. (HINT: Your answer should begin with an action potential arriving at an axon terminal.) 5 points
3. What events account for the synaptic delay? 2 points
4. Give one example of a chemical synapse that we have discussed in BIOL 2120K. 3 points

Answer 1

Chemical Synapse
Chemical synapse is the junction between a nerve fiber and a muscle fiber or between two nerve fibers, through which the signals are transmitted by the release of chemical transmitter. In the chemical synapse, there is no continuity between the two neurons because of the presence of a space called synaptic cleft between the two neurons.
Action potential reaching the presynaptic terminal.   Vesicles of the axon terminals are triggered.   
Release of neurotransmitter substance from the vesicles of this terminal.
Neurotransmitter reaches the postsynaptic neuron through synaptic cleft .   
This causes the production of potential change.   

SYNAPTIC DELAY
Synaptic delay is a short delay that occurs during the transmission of impulses through the synapse. It is due to the time taken for:
i. Release of neurotransmitter
ii. Passage of neurotransmitter from axon terminal
to postsynaptic membrane
iii. Action of the neurotransmitter to open the ionic
channels in postsynaptic membrane.
Normal duration of synaptic delay is 0.3 to 0.5 millisecond. Synaptic delay is one of the causes for
reaction time of reflex activity.
Significance of Determining Synaptic Delay
Determination of synaptic delay helps to find out whether the pathway for a reflex is monosynapatic or polysynaptic.