So my understanding is that heat is simply the speed/velocity and kinetic energy of molecules.
I can understand that the hotter something gets, the more excited and higher velocity/kinetic energy molecules have. it is natural for me to sort of grasp how letting your skin molecules come into contact with that, it strips away your skins molecules and you get burned.
but what i dont understand is: Cold is supposed to be the opposite and molecules more or less at rest mean low temperatures.
How can stable/resting molecules hurt us when its not actively stripping away skin molecules etc?
In: Chemistry
Because the molecules need to move to do their job in our body. The colder a substance gets, the harder it is to make it flow. That means skin gets less elastic, blood moves slower, all sorts of biological functions go to rest. And that’s before we consider the unique property of water to expand when it freezes. When body cells reach freezing point the water in them makes them burst.
There’s a few contributing factors:
1. Especially with endothermic animals like us, proteins and hormones have an ideal temperature range in which they act. When too hot or two cold, those compounds work less effectively. Ever wonder why our testicles are dangling around inside a scrotum instead of protected within the body? It’s because the proteins responsible for sperm production work best a little bit below body temperature and cause faulty cell division otherwise. Likewise, muscle cells, such as the ones in your heart, won’t function properly because they rely on energetic particles within their structure in order to contract.
2. Below the freezing temperature of water, ice crystals begin to form. If they form inside your body’s tissues, the crystals will lacerate cell membranes, causing severe tissue damage. Frostbite, in other words.
Lots of things in your body need to have a certain amount of energy to do their jobs. As your body gets colder it risks losing that energy and sends signals to your brain to make you feel uncomfortable so that you warm up. If your body loses too much energy from being too cold, some important things called chemical reactions won’t happen – this can lead to death.
Before this, the body tries to save up the energy in the most important places (vital organs) by changing where the blood goes. This means that the less important places like fingers and toes can lose their blood supply and the cells can die.
So the cold is not actively damaging the body in the way heat can. It hurts us by stopping us from functioning normally.
your cells are little car engines.
cold engines don’t work as well (without antifreeze).
frozen engines don’t turn on at all.
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