What would be the effect on the EPSP if the concentration of the enzyme responsi

Question

What would be the effect on the EPSP if the concentration of the enzyme responsible for degrading the excitatory neurotransmitter increased dramatically in the synapse? What would be the effect on the EPSP if the concentration of the enzyme responsible for degrading the excitatory neurotransmitter increased dramatically in the synapse? What would be the effect on the EPSP if the concentration of the enzyme responsible for degrading the excitatory neurotransmitter increased dramatically in the synapse?

Explanation / Answer

It will decrease the magnitude of EPSP.

Reason:

When neurotransmitter substance is released at an excitatory chemical synapse, it acts to depolarize the postsynaptic neuron, sometimes with sufficient strength to induce an action potential in that neuron. The depolarization produced by a single excitatory synapse is usually insufficient to actually trigger a nerve impulse, but its effect is to excite the postsynaptic neuron.

EPSP’s are depolarizing postsynaptic potentials, moving the membrane potential temporarily toward the cell’s threshold for producing a nerve impulse.

EPSPs are long lasting, at least when compared with action potentials; EPSPs typically continue for 5 to 10 msec before their depolarizing effects are completely dissipated, in contrast to the 1-msec duration of a nerve impulse.

The size of the EPSP produced by a given amount of neurotransmitter increases with the size of the membrane potential of the postsynaptic cell. EPSPs are larger when the postsynaptic membrane is highly polarized than when it is relatively depolarized.

All EPSPs show a synaptic delay of approximately 1 msec, the time elapsing between the arrival of an action potential at the presynaptic element of the synapse. The presence of synaptic delay indicates conclusively that the EPSP cannot be the result of a spread of current from the presynaptic to the postsynaptic element.

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