What defines smell and taste?

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We all learnt that sound is basically vibration in the air, sight is rebouncing light (or photon emission) and feel is difference in pressure. It’s easy to replicate these three senses (Eg phone can emit sound, light and vibration) relatively.

But what “creates” smell and taste and why is it so hard to replicate?

In: Chemistry

Taste and smell are sensed by cells that have sensors for specific chemicals that are in gas phase in odors and dissolved in saliva (or mixed with it at least) for taste. Taste is more limited than smell in terms of number of receptors. The smell or flavor of a thing as a whole is basically the combination of all the receptors that are activated plus their proportional strengths (so something 90% X and 10% Y tastes different than the opposite proportions). Other factors also influence perceived smell and taste, like temperature. It’s difficult to replicate these things because you would need to know allllll the chemicals responsible for the flavor or smell and their proportions to reproduce them. Which is difficult to know and to synthesize.

Edit: added mow info

Smell and taste are some of our simplest senses. They just measure the presence of certain molecules that bump into the lining of your nose and your tongue. For instance, your tongue has receptors that send an electrical signal when they come into contact with a sugar molecule. This electrical signal is interpreted by your brain as ‘sweet’. If there are a lot of these sugar molecules, they’ll activate many receptors, so you get a stronger ‘sweet’ sensation.

These receptors work a bit like a lock that gets activated only by a key that fits. The ‘key’ in this case is a part of the molecule that’s pretty unique to sugar. Not entirely unique, though: artificial sweeteners consist of molecules that include a part with the same shape, which is why they also taste sweet: they also fit in the sweet-receptor’s ‘lock’, and thus produce the same electrical signal.

Other receptors (e.g. sour, bitter, etc.) have ‘locks’ that are sensitive to different ‘keys’. Smell is not much different in this than taste, except that you can distinguish way more separate smells than tastes. Also smell depends more on combinations of molecules activating receptors in recognizable patterns, compared to taste where each receptor by itself is responsible for a distinct taste sensation (this is simplifying things a bit, but broadly this is the case).

Smell contributes to the perceptual experience of flavor, which is why not all sweet things taste exactly the same. E.g. when you eat a piece of chocolate, your mouth (mostly) just detects a sweet taste, along with the presence of fat, but it’s your nose that detects the more complex aroma’s that give chocolate its distinct flavor. But these complex aroma’s are again just molecules, that fit into receptors in the lining of your nose.

It’s worth noting that your sense of smell isn’t processed the same way as your other senses. Smell is primal, the first since we ever had as life on this Earth was probably a type of smell, taste, or chemical sensitivity. modern humans have an olfactory bulb, which can process smells and direct your body accordingly, so you are capable of smelling things without being consciously aware of them cerebrally, a trick the other senses can’t do. This is why pheromones work the way they do. Taste is similar. Smell and taste are more directly wired into our limbic systems, certain tastes or smells will make you immediately vomit for example with no need to be aware of what they are. Pheromones help regulate almost every part of our social behavior.

Sight sound and touch all run through the cerebral cortex, but your sense of smell isn’t quite so limited. It may seem like your sense of smell is more limited, but in fact it’s doing all kinds of shit you don’t know about all by itself without any interaction from you.