Why do we shiver when we’re cold?

Imagine that it’s a freezing day, with snow piled up high and still falling and you wanted to go for a walk outside. So, you put on your extra fluffy pair of socks and very comfortable shoes and you step outside, without wearing one of the most important items of clothing, a coat. To say that you would be cold is an understatement but imagine what you would do. Now, that scenario is obviously unlikely (the first thing you would do is put on your coat before leaving anyway) but we can all agree that you would shiver and your teeth would chatter, which in fact are our body’s way of trying to warm you up.

Our body needs to be at a specific temperature (36.9oC to be exact) for two main reasons, one being that 36.9oC is the optimum temperature for body cells to function and for the enzymes in our body to work properly. If our body temperature is too low, then these enzymes would slow down and not be able to work quickly, and if our temperature is too high then these enzymes will lose its shape and won’t be able to work at all. This is homeostasis which is the body’s way of maintaining a stable internal environment despite internal and external factors in order to maintain the optimum conditions for our body to function.

Image by Jill Wellington from Pixabay

Our body temperature can be regulated through shivering, helping us to keep warm. Shivering occurs when your muscles contract and expand really quickly to produce heat to raise your body temperature. In fact, teeth chattering happens because your jaws are shivering. This physiological strategy prevents you from getting hypothermia and other conditions that can come from having a low body temperature. However, how does our body know exactly when we are cold?

Going back to our scenario, if we do step outside without first wearing a coat, there are receptors on your skin (these are basically special cells on your skin that can detect changes) which sense that you are too cold and sends a signal to your brain. Your brain, a co-ordination centre, processes this signal and then tells your muscles to shiver to help raise your body temperature. This response continues until your skin receptors no longer sense that your skin is too cold (at this point you probably just went back inside to get your coat).

This response is a negative feedback mechanism as your body detects a change in your internal environment and brings about the appropriate response to raise it or lower it back to the optimum. In order to correct a change in your body’s internal environment, your body must do the opposite thing so that the internal environment becomes stable. E.g. raise your temperature when you are too cold and lower your temperature when you are too hot.

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