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.
A floppy fabric pull-on hat, usually worn with its top flopped down. In red, it is now used as a symbol of Catalan identity. Baseball cap. A type of soft, light cotton cap with a rounded crown and a stiff, frontward-projecting bill.