Question

Impulses from the sending cell release chemical messengers called neurotransmitters into the cleft. These substances are signaling molecules that can cause a rapid change in the membrane potential of the receiving cell. These chemicals can either speed up or slow down the transmission. Describe the effects of various substances on the action of a synapse?

Answer 1

Various substances at a chemical synapse can either speed up or slow down nerve impulse transmission by acting as excitatory or inhibitory neurotransmitters, or by modifying neurotransmitter activity through mimicking, blocking, altering release, or affecting reuptake and degradation.

Step-by-step explanation:

Effects of Substances on Synaptic Action

At a chemical synapse, the transmission of a nerve impulse between neurons or from a neuron to another type of cell, such as a muscle cell, is a complex event involving various substances. Neurotransmitter chemicals released from the presynaptic cell into the synaptic cleft can have either excitatory or inhibitory effects on the postsynaptic cell. Excitatory neurotransmitters like acetylcholine and epinephrine increase the likelihood of an action potential by depolarizing the postsynaptic membrane. Conversely, inhibitory neurotransmitters such as serotonin and GABA decrease this likelihood by hyperpolarizing it. When bound to receptors on the postsynaptic cell, neurotransmitters change the cell's electrochemical potential, thereby influencing the initiation of a subsequent electrical impulse. Drugs and other chemicals can also affect synaptic action by mimicking or blocking the action of neurotransmitters, altering neurotransmitter release, or affecting the reuptake and degradation of these chemicals, thus modifying the response of the postsynaptic neuron.