timothy points out news of a study from the University of Maryland's School of Medicine that found bitter taste receptors on the smooth muscle lining airways in the lungs
"The taste receptors in the lungs are the same as those on the tongue. The tongue’s receptors are clustered in taste buds, which send signals to the brain. The researchers say that in the lung, the taste receptors are not clustered in buds and do not send signals to the brain, yet they respond to substances that have a bitter taste. ... 'I initially thought the bitter-taste receptors in the lungs would prompt a "fight or flight" response to a noxious inhalant, causing chest tightness and coughing so you would leave the toxic environment, but that’s not what we found,' says Dr. Liggett. ... The researchers tested a few standard bitter substances known to activate these receptors. 'It turns out that the bitter compounds worked the opposite way from what we thought. They all opened the airway more extensively than any known drug that we have for treatment of asthma or chronic obstructive pulmonary disease (COPD).'"