In order to understand how cold affects the body, it will be necessary to obtain a mental picture of the air-passages, that tract which reaches from the nose to the lungs and is lined throughout by a continuous mucous membrane.
First, there is the nose, which is the most common site of a cold, and usually the first to be affected, though in some individuals a cold habitually starts as an inflammation of the air tubes in the lungs and spreads upwards. In others, the larynx may be the first part to be implicated. The nose is divided into two cavities by a partition, the nasal septum. Opening in front on the face, the nasal cavities communicate behind with the upper or nasal part of the throat.
So far, then, we have reached a space common to breathing and food intake through the mouth, but this is almost immediately divided into two passages – the front one with which we are concerned, leading direct to the lungs, and the back one carrying the food to the stomach.
During each act of swallowing, a flap-lite structure, called the epiglottis, automatically screens off the front or lung passage from the throat and prevents food particles from taking the wrong course.
The constant swallowing of inflammatory discharge, such as may occur during a neglected chronic nasal catarrh, may lead to derangements of digestion and to poisoning of the whole system. For this reason, as well as for other equally important reasons, chronic Catarrh should never be ignored.