Our nose is not the only organ in the body that can smell the coffee or cigarette smoke in the air. Our lungs can do this too!
Scientists have discovered a new class of cells in our lungs that act as odour receptors, though they function a bit differently than the olfactory cells in our nose.
Unlike the receptors in your nose, which are located in the membranes of nerve cells, the ones in your lungs are found in the human airway - called pulmonary neuroendocrine cells or PNECs.
"Instead of sending nerve impulses to your brain that allow it to "perceive" the smell of a burning cigarette somewhere in the vicinity, these receptors trigger the flask-shaped neuroendocrine cells to dump hormones that make your airways constrict," said Yehuda Ben-Shahar, assistant professor of biology at Washington University.
"Our lungs and our gut are open to the external environment. Although they're inside us, they're actually part of our external layer. So they constantly suffer environmental insults. So it makes sense that we evolved mechanisms to protect ourselves," added Michel J. Welsh, MD, of University of Iowa Carver College of Medicine.
The cells might be responsible for the chemical hypersensitivity that characterises respiratory diseases, such as chronic obstructive pulmonary disease (COPD) and asthma.
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Patients with these diseases are told to avoid traffic fumes, pungent odours, perfumes and similar irritants, which can trigger airway constriction and breathing difficulties, said the study published in the American journal of Respiratory Cell and Molecular Biology.
The odour receptors on the cells might be a therapeutic target. By blocking them, it might be possible to prevent some attacks, allowing people to cut down on the use of steroids or bronchodilators, the study said.