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Name: matkru
Status: N/A
Age: N/A
Location: N/A
Country: N/A
Date: Around 1993

How does the nose distinguish between different smells? What exactly is it smelling anyway and is there any way to reproduce this?

The nose distinguishes between different smells via the nasal epithelium at the top of you nasal pharynx. That is a delicate membrane innervated by many nerve cells. Each nerve cell has many proteins embedded in its cell membrane. These proteins have complimentary shapes to certain chemical groups that elicit scents. When an odorant molecule binds to one of these proteins, the cell depolarizes (due to a second messenger system in the membrane). This depolarization propagates back to the part of the brain called the olfactory bulb, below the forebrain. There the information from different cells is sorted out and sent to other brain structures, and the subjective sense of "smell" is elicited. Distinguishing between different odors is possibly accomplished by comparing different inputs from nerve cells with different protein receptors in them, or by "labeled lines" of neurons with a mix of proteins in them that are complimentary to a mix of odorant molecules that make up a scent. I know of know mechanical process that approximates smell by spectroscopy can distinguish different molecules The answer I have given is for vertebrates but invertebrates and plants can also smell, although by different mechanisms. Smelling in general is the subjective sensation experienced when one's olfactory system detects a scent; it can not be approximated by any mechanical process that I am aware of, although spectroscopy can be used to distinguish between chemical milieus.

Jim Murray

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