Glossary of Terms
Receptors - Millions of protein molecules, posted like sentinels around a cell membrane to screen the environment for messages addressed to them. Receptors are highly selective, usually responding to only one type of directive. The meeting of a messenger molecule, or ligand, with its receptor initiates a reaction inside the cell that ultimately affects what the cell does.
Rubrospinal tract - One of the major descending nerve pathways from the brain to the spinal cord.
Courtesy Christopher Reeve Foundation