The nose is the organ responsible for the sense of smell. The cavity of the nose is lined with mucous membranes that have smell receptors connected to the olfactory nerve. The smells themselves consist of odour of various substances.
The smell receptors interact with the molecules of these vapours and transmit the sensations to the brain.
Fig No. 2.8 Structure of a Nose
The nose also has a structure called the vomer nasal organ whose function has not been determined, but which is suspected of being sensitive to pheromones that influence the reproductive cycle. The smell receptors are sensitive to seven types of sensations that can be characterized as camphor, musk, flower, mint, ether, acrid, or putrid. According to Jainism there are basically only two types of smells: pleasant and unpleasant.[41] The sense of smell according to Neuro science is sometimes temporarily lost when a person has a cold. Dogs have a sense of smell that is many times more sensitive than of human's.[42]