When You're the One Canceling a Flight. In defense of Spirit, most airlines operate on razor thin margins and refund dollars do add up. Even airlines that allow refunds-generally only under very special circumstances-may make you jump through hoops and even pay a fee.
Medical Definition of receptor. 1  1: a cell or group of cells that receives stimuli : sense organ. 2  2: a chemical group or molecule (as a protein) on the cell surface or in the cell interior that has an affinity for a specific chemical group, molecule, or virus.
, whether monitoring internal or instead external signals employ receptor proteins, by and large, to detect signals. Receptor proteins may be located at cell surfaces or within the interior of cells. They may detect hormones or instead keep track of what otherwise is going on in cell's environment. whether monitoring internal or instead external signals employ receptor proteins, by and large, to detect signals. Receptor proteins may be located at cell surfaces or within the interior of cells. They may detect hormones or instead keep track of what otherwise is going on in cell's environment.