What is a Sneeze?
A sneeze, also known as sternutation, is a sudden, forceful, involuntary expulsion of air from the lungs through the nose and mouth. It is typically caused by irritation of the mucous membranes of the nose or throat, serving as a protective reflex to clear foreign particles, irritants, or allergens from the respiratory tract.
The Sneeze Reflex Arc
The sneeze reflex is triggered when nerve endings in the lining of the nasal passages detect an irritant. These nerves send signals to a 'sneeze center' in the brainstem, which then coordinates a complex sequence of muscular contractions. This reflex involves muscles in the chest, diaphragm, vocal cords, back of the throat, and eyelids.
Common Causes of Sneezing
Irritants such as dust, pollen, pet dander, strong perfumes, cold air, or sudden bright light (photic sneeze reflex) can trigger a sneeze. Infections like the common cold or flu can also inflame nasal passages, making them more sensitive and prone to sneezing as the body tries to expel viruses and mucus.
The Purpose of Sneezing
The primary function of sneezing is to expel substances that could potentially harm the respiratory system. The high velocity and pressure of a sneeze are effective in dislodging and propelling these irritants out, acting as a vital first line of defense for the nose and lungs.