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.
This is because bottles and caps are made from different types of plastics. Polyethylene terepthalate (PET), or plastic #1, often comprises plastic bottle,s while polypropylene (PP), or plastic #5, often makes up the caps.