The nose is an organ used for smelling and breathing. If it is not working properly we cannot distinguish between foul smell and fragrance. Do you know how the nose detects smell?
The nose is composed of two bones and is situated between the eyes below the head and above the lips. These two bones form a kind of bridge. In between them lies a wall of cartilage which divides the nose into two parts called the nasal cavities. At the end of the nasal cavities lies a thin membrane called the mucous membrane which secretes a special fluid. This fluid keeps the nose wet. There are hairs inside the nose which prevent dust particles from entering the lungs. The air filtered by the nose goes to the lungs through the trachea.
The smell is detected by the cells present in the two olfactory nerves situated at the end of the nasal cavities. These cells are called ‘receptors’ and are embedded in the mucous membrane. They are spread over an area of 250 square millimetres.
According to one theory, our nose has seven kinds of receptors – each telling a different smell. The seven smells are of: flowers; burning; alcohol; fruits; peppermint; musky and pungent smell. When we smell something, particles coming out of it reach this sensitive area through the nasal cavities. They generate electric impulses in the nerves there. These electric impulses reach the ‘smell centre’ of the brain and we detect the smell.
We often confuse smell with taste because gaseous particles of many of the food we eat reach the receptors for smell as we eat. Food often seems to lose its taste when we catch cold. Our sense of smell is blocked during a cold attack, and this has an effect on our taste.