Calcium pump Calcium pump Calcium pumps are a family of ion transporters found in the cell membrane of all animal cells. They are responsible for the active transport of calcium out of the cell for the maintenance of the steep Ca electrochemical gradient across the cell membrane. Calcium pumps play a crucial role in proper cell signalling by keeping the intracellular calcium concentration roughly 10,000 times lower than the extracellular concentration. Failure to do so is one cause of muscle cramps. The plasma membrane Ca ATPase and the sodium-calcium exchanger are together the main regulators of intracellular Ca concentrations. Ca has many
Symbol table global scope, whether it is imported, and what namespace it belongs to. Some programming languages allow the symbol table to be manipulated at run-time, so that symbols can be added at any time. Racket is an example of such a language. Both the LISP and the Scheme programming languages allow arbitrary, generic properties to be associated with each symbol. The Prolog programming language is essentially a symbol-table manipulation language; symbols are called "atoms", and the relationships between symbols can be reasoned over. Similarly, OpenCog provides a dynamic symbol table, called the "atomspace", which is used for knowledge representation. Symbol table