The human body has one job, and that is to keep itself alive. Luckily for us, it's pretty good at it, and it'll take some pretty extreme measures to do so.

In that respect, frostbite is the body's survival instinct kicking in; effectively sacrificing your extremities in order to protect your internal organs.

As the temperature drops to dangerous levels, your body pulls blood away from parts of your body that are closer to the source of the cold; your nose, fingers, toes, etc... and redirects it to your organs and your core in order to protect them from what it sees as the more serious threat, hypothermia.

As the blood retreats, those extremities begin to feel numb and tingly.

Stay out with exposed skin much longer than that, and the cells that are now lacking the oxygen from the constant blood flow begin to starve, while at the same time facing a new enemy from within; ice crystals.

Water gets drawn out of the cells and crystalizes in the space between the cells, damaging some and outright killing others.

Once it's reached this point, even getting out of the cold is not an easy solution for the damage that may have begun to take hold.

As the tissues begin to warm and the capillaries in your extremities open up to blood flow again, the damaged tissues have to contend with what is called "reperfusion damage" causing blood pooling, inflammation, excess fluid, clotting, and other complications.

Re-warm your extremities too quickly, by dunking them immediately in hot water, for example, and you risk permanent damage that may take weeks, or even months to fully show itself as damaged cells heal (or die off) at different rates.

This is why medical professionals recommend warming your frostbitten extremities slowly, using body heat from an armpit or a groin, or warm water of around 40 degrees Celsius.

It's why medical professionals caution frostbite sufferers to not rub their extremities to force feeling and warmth back into them, as this is doing nothing except potentially causing more damage to already damaged cells.

But of course, as they say, an ounce of prevention is worth a pound of cure.

With the extreme windchills likely sticking around for a few more days at least, and with seasonal temperatures likely still a couple of weeks away, the easiest way to treat frostbite is to not be in the position to get it at all.

Cover exposed skin. Limit the time spent outdoors. Dress in multiple layers with an outer layer that blocks the wind.

For more information on frostbite and a deeper dive into prevention and first aid, visit the St. John Ambulance Canada website here.