Science behind the sneezing

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Science behind the sneezing 

Sneezing is a physiologic response to the irritation of the respiratory epithelium lining of the nose. The process usually begins with the release of chemicals such as histamine or leukotrienes. These substances are manufactured by inflammatory cells such as eosinophils and mast cells typically found within the nasal mucosa. Chemical release is caused by viral respiratory infections, filtered particles, allergens (substances that trigger allergic reactions) or physical irritants such as smoke, pollution, perfumes and cold air. 

Allergic reactions with the nasal mucosa require the presence of IgE (allergy antibody specific for the allergen). This leads to fluid leakage from vessels in the nose, causing symptoms of congestion and nasal drip. Additionally, nerve endings are stimulated, leading to the sensation of itching.


Ultimately, the nerve ending stimulation leads to activation of a reflex inside the brain. The nervous impulse travels up the sensory nerves and down the nerves controlling muscles in the head and neck, and that leads to the rapid expulsion of air. 

The high velocity of the airflow is achieved by the buildup of pressure inside the chest with the vocal chords closed. Sudden opening of the cords allows the pressurized air to flow back up the respiratory tract to expel the irritants.

 This helps to remove offending particles in the nose. However, in infected individuals, it also allows for the spread of the common cold, as innumerable viral particles are contained within each droplet of mucus expelled.

Does our heart stops while sneezing?


sneeze begins with a tickling sensation in the nerve endings that sends a message to your brain that it needs to rid itself of something irritating the lining of your nose. You first take a deep breath and hold it, which tightens your chest muscles.  The pressure of air in your lungs increases, you close your eyes, your tongue presses against the roof of your mouth and suddenly your breath comes out fast through your nose.

So where did the myth originate that your heart stops when you sneeze?  The changing pressure in your chest due to sneezing also changes your blood flow, which may change the rhythm of your heartbeat. 

Dr. Richard Conti, past president of the American College of Cardiology, speculates that the belief that the heart actually comes to a stop during a sneeze could result from the sensation of having the heart "skip a beat." When there is a prolonged delay before the heart's next beat, he said, that beat is then more forceful and more noticeable, perhaps as a funny sensation in the throat or upper chest (Ray, 1992).




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