The nose is an indispensable organ that is used for breathing and sense of smell. If it is not working properly, we cannot distinguish between foul smell and fragrance. Do you know how the nose detects smell? The nose may look like a very simple structure but it is very complicated in nature. 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 moist. The hair inside the nose waves back and forth to prevent dust particles, bacteria and fluids from entering the lungs. So the air that goes into the lungs through the trachea has already been filtered by the nose. 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. It is believed that the sense of smell is closely related to that of taste. Did you know that if a man was blindfolded and his nose was blocked, he would not be able to differentiate the taste between a potato and an apple?