Synapse

   This is the gap between two neurons, where the nerve impulse is transmitted by a chemical neurotransmitter, such as acetylcholine. Molecules of the neurotransmitter are released into the synapse by the end bulb (axon terminal) of the presynaptic neuron to bind to receptors on the surface of the postsynaptic neuron on the far side of the synapse. The neurotransmitter is then reabsorbed into the presynaptic neuron in a process known as "transport," or "reuptake."

   The term "synapse" was coined by London neurophysiologist Charles Scott Sherrington (1857–1952) in 1897 in an article in Michael Foster’s (1836–1907) Text-Book of Physiology; Sherrington hypothesized that a functional connection must exist between nerve cells, one that he initially called a "synapsis" (from the Greek "to clasp"), but that quickly morphed into synapse. Evidence for the chemical transmission of the nerve impulse was clinched by the Graz professor of pharmacology Otto Loewi (1873–1961) in 1921 in an epochal article on "vagus material" (Vagusstoff ) that he wrote in Pflügers Archive for Physiology (Pflügers Archiv für die gesamte Physiologie), "On Humoral Transmission as the Mechanism of the Heart Nerves" (Über humorale Übertragbarkeit der Herznervenwirkung"). Loewi later conceded that the "Vagusstoff" must be acetylcholine, the physiological action of which had been discovered by his friend, the London physiologist Henry Hallett Dale (1875–1961), and discussed in 1914 in the Journal of Pharmacology and Experimental Therapeutics. For his achievement, Loewi won a Nobel Prize in 1936.