Olfactory epithelium has cells {basal cell} that can become olfactory neurons.
Olfactory-receptor cells send to neurons {mitral cell}, whose top dendrites go to horizontal cells to receive lateral inhibition and whose bottom branches are recurrent collateral axons to spread lateral inhibition. Mitral-cell axons go to anterior-olfactory-nucleus and prepyriform-cortex superficial and deep pyramidal neurons.
Olfactory-receptor cilia have molecules that bind odorants. Smell system has a thousand different protein receptors {olfactory receptor}, with seven to eleven major odor-receptor types, which each have a dozen minor types. People have ten million odor-receptors in each nostril. Dogs have 200 million. Odor-receptors die every month, and then new ones grow.
Of 1000 olfactory-receptor genes, 65% are not functional in humans. In Old World monkeys, 30% are not functional. In New World monkeys, 18% are not functional. In dogs, 20% are not functional. Odor-receptor chemical sites are for alcohols, aldehydes, amines, aryls, carboxylic acids, esters, ethers, halogens, ketones, cysteines, thiols, sulfides, or terpenes. Sites can be for small, medium, or large molecules [Firestein, 2001] [Laurent et al., 2001]:
Alcohols that are small, such as methanol and ethanol, smell alcoholy, biting, and hanging.
Alcohols that are medium-chain, such as butanol and octanol, smell sweet and fruity.
Alcohols that are cyclic, such as menthol, smell cool and minty.
Alcohols that are monoterpenoids, such as geraniol and linalool, smell flowery and fresh.
Alcohols that are monophenols, such as phenol and guaiacol, smell burnt and smoky.
Alcohols that are polyphenols, such as cresol, smell tarry and oily.
Aldehydes that are small, such as diacetyl aldehyde, smell buttery.
Aldehydes that are short-chain, such as isovaleraldehyde, smell malty.
Aldehydes that are alkene aldehydes, such as hexenal, smell grassy and herby.
Amines that are alkyl and aryl monoamines, such as trimethylamine and phenethylamine, smell fishy.
Amines that are alkyl multi-amines, such as putrescine, smell spermous.
Amines that are heterocyclic amines, such as pyrroline, smell spermous.
Amines that are heterocyclic aromatic, such as alkyl pyrazines, smell nutty, earthy, and green peppery.
Amines that are heterocyclic aromatic, such as 2-acetyl-tetrahydro-pyridine, smell roasted, fermented, and popcorny.
Aryls that are benzene alkyls, such as benzene, toluene, and xylenes, smell aromatic.
Aryls that are monophenols, such as phenol and guaiacol, smell burnt and smoky.
Aryls that are polyphenols, such as cresol, smell tarry and oily.
Aryls that are polycyclic aromatic hydrocarbons, such as anthracene and pyrene, smell burnt and smoky.
Aryls that are polycyclic in small concave sites, such as camphor, smell camphorous and resinous.
Aryls that are aryl monoamines, such as phenethylamine, smell fishy.
Carboxylic acids that are small, such as acetic acid, smell acrid, vinegary and pungent.
Carboxylic acids that are medium-short polar chains, such as butyric acid (butanoic acid), smell putrid, sweaty and rancid.
Carboxylic acids that are medium-length polar chains, such as caprylic acid (octanoic acid), smell goaty and hircine.
Carboxylic acids that are carboxylic-acid thiols, such as dithiolane-4-carboxylic acid, smell asparagusy and bitter.
Esters that are non-polar chains, such as methyl butyrate, smell sweet and fruity.
Ethers that are linear in concave and trough-shaped sites, such as ethyl methyl ether, smell fragrant, ethereal, floral and flowery.
Ethers that are cyclic, such as dioxacyclopentane, smell earthy, moldy and potatoey.
Halogens, such as fluorine, chlorine, and bromine, smell pharmaceutical, medicinal, pungent, and unpleasant.
Ketones that are heterocyclic, such as furanone and lactones, smell savory and spicy.
Ketones that are alkane ring ketones, such as steroid ketones, smell urinous.
Ketones that are macrocyclic in large concave sites, such as muscone (methylcyclopentade-canone), smell musky and ambrosial.
Ketones that are alkenes with one ring, such as ionones, damascones, and damascenones, smell tobaccoy.
Ketones that are cyclic alkene ketones in V-shaped sites, such as terpenoids and R-(-)-carvone (2-methyl-5-(1-methylethenyl)-2-cyclohexenone), smell minty, spearminty, and pepperminty.
Sulfur compounds that are cysteines, such as gamma-glutamylcysteines and cysteine sulfoxides, smell alliaceous and garlicy.
Sulfur compounds that are carboxylic-acid thiols, such as dithiolane-4-carboxylic acid, smell asparagusy and bitter.
Sulfur compounds that are small thiols, such as methyl mercaptan (methanethiol), smell foul, sulfurous, and rotten.
Sulfur compounds that are sulfides, such as methyl sulfides, smell cabbage-like and rotten at high concentrations.
Terpenes that are cyclic alkene ketones in V-shaped sites, such as terpenoids and R-(-)-carvone (2-methyl-5-(1-methylethenyl)-2-cyclohexenone), smell minty and pepperminty.
Terpenes that are monoterpenoid alcohols, such as geraniol and linalool, smell flowery and fresh.
Terpenes that are isoprenes and monoterpenes, such as isoterpene, smell rubbery.
Terpenes that are sesquiterpenes and triterpenes, such as humulene, smell woody.
Some sites are for both alcohol and terpene, alcohol and aryl, amine and aryl, carboxylic acid and thiol, or ketone and terpene.
Some sites are for carbon chains and rings: alkyls, alkenes, single rings, multiple rings, single heterocyclic rings, multiple heterocyclic rings, single aromatic rings, and multiple aromatic rings.
1-Consciousness-Sense-Smell-Anatomy
Outline of Knowledge Database Home Page
Description of Outline of Knowledge Database
Date Modified: 2022.0225