Smell is a very important function of the human body. Essentially each thing which has a good odor or a bad one gives off certain molecules which come to one’s nose. Usually these molecules are very light and they evaporate easily in to one’s nose. It is through the sense of smell that one can differentiate between a good, bad or pungent smell. One would be surprised to know that human beings can distinguish 10, 000 and more smells.
Description of the nose
The composition of a nose is of two bones which form a bridge. A cartilage which takes the form of a wall separates the nose into two parts which are called nasal cavities. There is a thin membrane which is positioned at the extreme end of the nasal cavities called mucous membrane. The nose is moist by a fluid secretion from the mucous membrane.
Mechanism
At the end of the nasal cavities are two olfactory nerves. These nerves have certain cells called receptors. The area of these cells is barely 250 square millimeters. These olfactory receptors are numerous and each are encoded uniquely a separate gene and thus can recognize different smells. However in the event of a damage of any DNA which misses a gene, one might not be able to smell a particular odorant. The receptors are widely divided in seven broad categories of burning, flowers, pungent, fruits, alcohol, peppermint and musky.
In case of some molecules coming out of a particular thing emitting smell, some electric impulses might be generated by the nerves and receptors. These electric smells immediately traverse the smell center of the brain which sends feedback that enables one to detect the smell. In case if one is suffering from a cold, usually one loses the sense of smell since the sensitive cells or the receptors are all covered.
