In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell.——————Neurotransmitters are endogenous chemicals that enable neurotransmission. It is a type of chemical messenger which transmits signals across a chemical synapse, such as a neuromuscular junction, from one neuron (nerve cell) to another "target" neuron, muscle cell, or gland cell.
<h3><u>One of the reasons we can't get an accurate count is that the bulk of the things that have yet to be discovered and described are in the realm of the very small: insects, bacteria and other microbes</u></h3>