In the face of cold weather, our body may reduce blood flow at the skin and the body’s extremities. VCG
Cold air has hit China as we enter deep winter. Going outdoors, you may feel the cold wind trying to penetrate your coat, hitting body parts covered by little material – such as the face. To explore how our bodies respond to coldness, let’s first explore how we feel “cold”.
Human skin is filled with temperature-sensing nerve receptors named TRP, and they receive stimuli from the environment. Such stimuli may be pressure, cold, heat, or chemical, etc. To sense cold, the brain uses a kind of receptor called TRPM8.
Scientists first studied TRPM8 in 2002, discovering that its stimuli include a temperature between 10 C and 30 C and menthol. This is also why mint-flavored toothpaste can make our mouths cooler and fresher. When the TRPM8 is hit by stimuli, it sends an electric signal to the brain which understands the signal as “cold”.
The body then protects itself from the cold through different means. According to Live Science, the body slows down its muscles and the nervous system. In this way, it reduces heat loss.
The cold also leads to less blood flow. The body will first reduce blood flow at the skin and the body’s extremities, including the fingers, hands and feet. This is why these parts tend to feel cold first.
“We try to limit how much blood we send out there, so it limits how much heat we put into the environment,” John Castellani at the US Army Research Institute of Environmental Science told Live Science.
To bring the body’s temperature back up, the body tends to produce heat itself by allowing muscles and organs to shake, more commonly known as shivering. Although this attempt may not be effective, it is more like a warning to people about the cold. In extreme cases, the body may be unable to maintain its core temperature inside, leading to injuries such as frostbite.