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| The Nose and Smell |
The nose helps us in breathing and smelling things. The outer side of the nose is made of thick skin which is supported outwards with the help of a cartilage protruding outwards from the skull. The cartilage divides the nose from the center thus giving us the two nostrils, at the rear these nostrils end up into a common cavity leading into the throat. Also leading into the nose cavity are the tear ducts from the eyes, which allow water from the eyes to flow out through the nose. As we breathe in, air is ingaled through the nose and it flows down the nasal path into the windpipe and subsequently into the Lungs, the process is reversed when we exhale.
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Since we breathe through our nose, a lot of foreign bodies and particles enter our body. The bigger ones get caught in the hair inside our nose but when infective viruses enter our nose, they attack the linning of the nose and throat and cause inflammation. This results in the production of mucus and gives us a running nose and a cold. Mucus is pushed downwards into the nasal cavity and throat from where it goes down into the oesophagus and then into the stomach where it is dealt with by the body’s defense mechanisms. Mucus can also be let out by exhaling wind with a force through the nose, called blowing the nose.
Another important function performed by the nose is to provide us with the ability to be able to smell things. On the roof of the nasal canal are located a number of small ‘smell receptors’. The smell receptors have small hair like projections which project into the nasal cavity through the mucus lining. When molecules in the air dissolve in the mucus, they stimulate these receptors and we are able to smell. Though the receptors are only of about 15 different types, they can detect over 10,000 different smells. Our sense of smell is useful to us when we are eating something because it forewarns us in case the food is stale or bad.
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Medical