Why we Shiver when we cold

For the second time this year i have a cold, this one dosent leave you with a dripping nose or what you normally consider as a cold, it leaves you with a dry cough almost like you have the flu, i have to check how i am typing this as my brain is not functioning to well for now, its very sluggish and uncoordinated

One thing i wondered though was why we shiver when we are cold and this is why...

Simple explanation

The hypothalamus, a part of the brain senses the the temperature of the blood and compares it with a setpoint of what it should be, by shivering the movement of the muscles is converted to heat

More in-depth explanation

The hypothalamus, a part of the brain just above the pituitary gland, contains the body's thermostat.It senses the temperature of the blood and compares it with a setpoint — the desired temperature. 

If the actual temperature differs from the setpoint, it tries to adjust the temperature. This is similar to what a thermostat in your house or car does. However, it can't just turn on the furnace or the air conditioner.

Instead, it sends out signals that cause us to sweat if we are too hot or to shiver if we are too cold. (Sweating cools the body as the sweat evaporates; shivering warms the body, because much of the energy used by shivering muscles is converted to heat.).  In addition, it causes us to feel uncomfortable, which prompts us to seek out a source of heat or cold. For example, if your body temperature is too low, you'll look for a warmer place or some blankets, sweating you'll look for a cooler spot or reduce your exercise level (since exercise generates heat). 

If you want to know more i got the information from this page

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