Unlike an electrical synapse, the chemical synapses are separated by a space called the synaptic cleft, typically measured between 15 and 25 nm. Transmission of an excitatory signal involves several steps outlined below.
Definition of cap. 1  1a : a head covering especially with a visor and no brimb : a distinctive head covering emblematic of a position or office: such as (1) : a cardinal's biretta (2) : mortarboard.
Word Origin and History for cap Expand. n. late Old English cÃ¦ppe hood, head-covering, cape, from Late Latin cappa a cape, hooded cloak (source of Spanish capa, Old North French cape, French chape), possibly a shortened from capitulare headdress, from Latin caput head (see head (n.)).