Receptor: 1. In cell biology, a structure on the surface of a cell (or inside a cell) that selectively receives and binds a specific substance. There are many receptors.
The most common is EPNS (Electro Plated Nickel Silver) but many other symbols are used: 1  EPBM (Electro Plated Britannia Metal). 2  EPCA (Electro Plated Copper Alloy). 3  ESM (Electro Plated Silver Mounts).he most common is EPNS (Electro Plated Nickel Silver) but many other symbols are used: 1  EPBM (Electro Plated Britannia Metal). 2  EPCA (Electro Plated Copper Alloy). 3  ESM (Electro Plated Silver Mounts).
Circuit Switching. The PSTN is what is known as a circuit switching network. In other words, when a telephone call is made, an exclusive dedicated circuit is established and only released when the call ends.hares & Saves. Save. PSTN is an abbreviation for Public Switched Telephone Network and is used to describe a network of interlinked telephone systems---state-owned or commercial---and includes everything but private telephone systems that are managed by their own PBX (Private Branch eXchange).