: How do humans feel temperature differences and how precisely can we feel it?
In: Biology
Your cells express receptors from the TRP family. These receptors are proteins which sit on the outside of nerve cells, and when they’re activated they start a signal which is relayed to your brain to cause a sensation. Lots of receptors work by recognising a very specific molecule. This will bind to them (through specific combinations of electrostatic charges on the molecule and on the receptor), causing the receptor to change its shape to the ‘active’ configuration, allowing ions to move through and cause the signal (think of a lock and key, where the lock is a receptor in your taste bud, the key is salt, and the door opening is you getting the salty flavour).
Some of these TRPpy bois are a bit different from ‘regular’ receptors. Rather than recognising specific molecules, they are sensitive to temperatures. At 30 degrees they’ll be closed, but maybe at 40 degree the temperature will be high enough to overcome some of the electrostatic attractions within the receptor itself, changing its shape to ‘open’ and causing a signal. Your body encodes tonnes of these receptors and they’re all sensitive to slightly different temperatures. Some are linked to cells which let you detect temperature, and some are linked to nerves which make you go ‘oh fuck that’s hot ow’, and some link straight into your reflex to withdraw your body from the heat because it’s hot enough to damage you.
As for the why – evolution. Organisms which could tell dangerous and safe temperatures apart didn’t die and reproduced, and then it got really complicated over time, then here we are.
Fun fact – chillies contain capsaicin. Rather than activating your ‘ow fuck that’s hot’ receptors, they actually bind to them and slightly change the shape, not quite opening them but making them more susceptible to lower temperatures. That’s actually why we feel the heat – it’s not that the chillies are that temperature.
I realise this ain’t ELI5 very well but I’m a scientist not a teacher. Sorry all. For further reading this is the first thing I found on Google. Enjoy – https://www.ncbi.nlm.nih.gov/pubmed/29135465/
Also I realise I’m the only one not talking about thermodynamics and why different materials feel different. But I love this shit and wanted to feel included OKAY
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