local response,effect surrounding cells,receptors,receptor specific,interstitial fluid,acts on cells surrounding secretor,localized,no bloodstream travel,exert an effect,acts on nearby receptors,receptor,nearby communiucation with receptor,act on neighboring cell,adjacent cells,nearby cell,substance acts on adjacent cell,acts next to,effect via interstitial fluid,act on nearby cells,acts on cells near by,surrounding cells,diffusion,