ear, nose, and throat disorders
Nose and Sinuses
Sense of smell
One of the most important functions of the nose is its role in the sense of smell. Smell receptor cells are located in the upper part of the nasal cavity. These cells are special nerve cells that have cilia. The cilia of each cell are sensitive to different chemicals and, when stimulated, create a nerve impulse that is sent to the nerve cells of the olfactory bulb, which lies inside the skull just above the nose. The olfactory nerves carry the nerve impulse from the olfactory bulb directly to the brain, where it is perceived as a smell. The sense of smell, which is not fully understood, is much more sophisticated than the sense of taste. Distinct smells are far more numerous than tastes. The subjective sense of taste while eating (flavor) involves taste and smell (see figure) as well as texture and temperature. This is why food seems somewhat tasteless when a person has a decreased sense of smell, as may occur when the person has a cold. Because the smell receptors are located in the upper part of the nose, normal breathing does not draw much air over them. Sniffing, however, increases the flow of air over the smell receptor cells, greatly increasing their exposure to odors. 