The automatic response of trying to take a deep breath or choking when something is introduced into the back of the mouth and throat. It is the way we protect ourselves from inhaling food or other unwanted material into the lungs. The first part of assessing an accident victim or one unconscious for another reason is to check that their airway is open – that is, that from mouth to lungs there is no obstruction. The reason for doing this is that they may have lost their gag reflex so cannot clear their own airway by coughing or gagging. Any false teeth, vomitus and foreign bodies should be removed, and the response to stimulating the back of the throat with the examiner's finger checked. If the gag reflex is absent or impaired, an ENDOTRACHEAL tube should be inserted.