The reaction of the human body in freezing temperatures

When the body's central temperature drops to 21 degrees C or below, people are at a higher risk of death.

Body core temperature, also known as central temperature, is always around 37 degrees Celsius. Hypothermia occurs when the central temperature drops to 35 degrees C or below. People may experience hypothermia in relatively cold conditions but not yet freezing (from -1 to 10 degrees Celsius), especially if they are wet such as dripping rain, sweating or soaking in cold water. Underwater, the body loses heat about 25% faster than on land, according to Michael Sawka, director of the US Army's Institute for Environmental Medicine Research (USARIEM).

Humans begin to hypothermia when the central temperature drops from 35 degrees Celsius (Image: iStock).

At -34 degrees Celsius, a healthy person who doesn't wear warm enough can experience hypothermia within 10 minutes. Between -40 and -45 degrees Celsius, hypothermia can occur after 5-7 minutes.

A drop in body temperature will prevent important organs from functioning properly, including the brain and heart, according to the Mayo Clinic. The result is a reduced blood flow to the internal organs, which puts the body in a state of shock and increases the risk of liver and kidney failure, according to Lenox Glatter, an emergency physician at Lenox Hill Hospital, New York. Younger or older people are at higher risk of hypothermia due to weak heart muscle.

Mild hypothermia symptoms such as tremor, weakness and confusion occur when the central temperature is about 35 degrees Celsius. At 33 degrees Celsius, you may suffer from memory loss. With a body temperature of 28 degrees Celsius, you will lose consciousness. From 21 degrees C and below, you are at risk of death. The record of the lowest body temperature at which an adult can survive is 13.7 degrees Celsius, according to researcher John Castellani at USARIEM. When left untreated, hypothermia can cause heart failure and death.

The human body has two mechanisms for dealing with cold conditions. As soon as the cold wind hits the face, the body will pump blood from the skin to the protruding parts like fingers and toes, and to the core. This process, called vasospasm , helps limit the amount of heat released into the environment. The second reaction is shivering, which contributes to heat production and raises body temperature.

1. Why do people take their clothes off when they are about to freeze to death?