What Happens to Your Body When You Get Cold: Hypothermia
Although it would be great if we could pile on a bit of weight, wrap up warm and dig a hole to sleep in until the start of spring, human’s aren’t really designed for hibernation. Thankfully, we are equipped with bodies that can deal with the usual changes in temperature through the seasons.
However, the human body does tend to manage overheating more effectively than getting cold. So in case you were wondering why you feel the need to rush out and buy a big woolly jumper and economy radiator when the weather starts getting a bit chilly, that would be why.
There are a number of mechanisms in our bodies that can sense changes in temperature and react accordingly. These measures kick in when our body temperature starts to fluctuate too much in either direction. Whilst these processes can cope with the cold to a certain extent, after a prolonged period of exposure to very cold temperatures they can get overwhelmed.
Hypothalamus – Your Internal Thermostat
Just like the central heating system in your house, everyone has their own internal thermostat called the hypothalamus. This part of your nervous system recognises when any part of your body is getting cold and engages a series of heat retention processes which, in extreme cases, operate at the risk of other parts of your body in order to maintain core temperature. As with the rest of your autonomic nervous system, these actions are involuntary and kick in without any rubbing of hands or jumping up and down!
Factors that can determine or alter how effectively your hypothalamus operates vary. They include things like underlying health conditions such as diabetes or hepatitis. Age and just general wellbeing also come into play when it comes to homeostatic processes.
How Your Body Maintains Temperature
When your body starts to react to the cold, the blood vessels closest to the surface of your skin shrink in order to reduce heat loss from the skin’s surface. You begin to shiver, which are muscle spasms designed to generate body heat. As you will probably have experienced, this can occur in any muscle of your body, but most commonly includes chattering teeth.
The hairs all over your body will stand on end, in an attempt to create a pocket of air to trap warmth against the surface of your skin. Obviously, this isn’t quite as effective as a few million years ago when our bodies were completely covered in fur, but it does still have a limited effect. If these processes aren’t enough and your core temperature does start to drop, this sequence of events usually follows.
Stages of Hypothermia
- When your core temperature hits 35 degrees C, the shivering previously mentioned starts. (stage 1 of hypothermia)
- If it drops just one more degree, you might start to feel disorientated and slur your speech.
- At 33 degrees your muscles seize up and your pulse slows dramatically. (stage 2 hypothermia)
- You begin to feel sleepy at 32 degrees. (stage 3 hypothermia)
- Once your core hits 31 degrees severe hypothermia sets in and you will barely respond to stimuli.
- You will slip out of consciousness at 30 degrees C and your pupils will dilate.
- Your pulse will be undetectable at 29 degrees.
- If your core reaches 28 degrees, you won’t be able to be revived and will appear dead.
- You’ll completely stop functioning when your core body temperature reaches 26 degrees centigrade.
Thankfully, there are only a few places in the world where we might experience these sorts of temperatures for a prolonged period. We have also developed additional methods of keeping ourselves warm, even in these extreme environments.