Kýchání

Kýchání, also known as sneezing, is an involuntary expulsion of air from the lungs through the nose and mouth. It is a reflex action that helps to clear the nasal passages of irritants such as dust, pollen, or other allergens. The reflex is triggered by stimulation of the mucous membranes in the nose.

The process of sneezing involves several steps. First, the person takes a deep breath. Then, the glottis, which is the opening between the vocal cords, closes, and the diaphragm contracts. This builds up pressure in the lungs. Finally, the glottis opens suddenly, and the air is expelled rapidly, carrying with it any irritants present in the nasal passages.

Sneezing can be caused by a variety of factors. Common triggers include allergies, infections like the common cold or flu, exposure to irritants like pepper or strong perfumes, and sudden changes in temperature. Some individuals may also sneeze in response to bright light, a phenomenon known as the photic sneeze reflex.

While sneezing is a natural bodily function, frequent or excessive sneezing can sometimes indicate an underlying medical condition. If sneezing is accompanied by other symptoms such as fever, persistent cough, or difficulty breathing, it is advisable to consult a healthcare professional. In most cases, however, sneezing is a harmless and beneficial reflex.