If you put your finger in hot water for a split second your body's normal reaction from the pain receptors will tell your body to remove your finger from the hot water and pull your hand away and out of the hot water.
If the water is hot enough then you should immediately pull your finger out of the hot water and may not even get a burn or you may just get a small blister.
putting your finger into boiling hot water even for a split second will likely cause a burn or blister and some pain.
When you put your hands in water for a long time the hands become wrinkled because your nervous system will send a message to the blood vessels to shrink and your skin becomes wrinkled.
The wrinkling is an autonomic nervous system response which helps you grip wet objects easier and it's caused by blood vessel shrinkage, nerve fiber shrinkage, loss of volume, loss of natural oils and loss of plasticity.
The benefits of soaking your hands in hot water are pain relief, reduced swelling, improved circulation, stress relief, reduced stiffness
Soaking your hands in hot water can relieve pain and stiffness in joints and muscles by increasing blood flow which also causes chemical and speeds up the healing process.
Warm water can also help reduce swelling and inflammation and the heat helps the cells regenerate by increasing the blood flow.
You should don't want to soak your hands in water that is too hot or put cold hands into hot water.
The reason you can't put cold hands in hot water is because you risk burning your hands and cause tissue damage.
When the skin of your hands are cold or extremely cold the cold hands and skin become less sensitive to temperature changes which makes you more prone to burns.
This is because you may not feel the intense heat until severe damage is already done, especially if you have frostbite where your skin is numbed.
The rapid warming of the cold skin with hot water can actually cause severe burns because of a lack of sensation.
If your hands are also frostbitten the cold water can also worsen the damage from the frostbite.
If your hands are very cold you should gently warm the hands up with lukewarm water or use a warm washcloth to gradually restore the blood circulation.
To warm your hands, feet or ears when they are cold put cold hands, feet, or ears in warm (not hot) water for 15 to 30 minutes.
Do not use water above (108°F).
Warm towels can be used to warm the genital area but be careful not to burn the skin.