The normal temperature of the human body (37ºC) is regulated by a region of the brain called the hypothalamus – it makes us sweat when the body needs to cool down and makes us shiver when we need to preserve heat in the body. If the external cold is too intense, the first area to be affected is precisely the hypothalamus, which ends up losing this ability to adjust our temperature. As all chemical reactions within our body need heat to take place, a very cold temperature causes vital functions to slowly slow down. “If the person is unclothed, below 28ºC they enter a state of hypothermia – which means lack of heat for the body to work”, says physiologist Mauro Antônio Griggio, from Unifesp. Simply put: the heart, which needs energy – and, consequently, heat – to beat, begins to slow down. The same happens with breathing, which needs muscle contraction to function.
As the transmission of impulses from the central nervous system also needs heat, the individual begins to lose sensitivity. That way, he loses consciousness until his heart stops for good. The time it takes a person to die of cold varies according to certain circumstances: if it is windy, for example, it is shorter, as the wind cools the body much more easily. “At a temperature of 10ºC, which is already quite aggressive for the human body, this process can take about five hours to happen – if the person is well nourished and warm – unfortunately, this is not usually the case for most people who die in these temperatures. conditions: in general, they are homeless”, says Mauro.