Temperatures are expected to approach 40°C in the coming days. These high temperatures affect our organs and can be dangerous.
I m subscribe to 1€ for the 1st month
From this Wednesday, June 15, 2022, the southern half of France should experience an early and intense heat wave. According to Météo-France, temperatures should be around 40°C. This type of episode affects our daily life: we are more tired, less dynamic, borderline overheated…
In France, after the 2003 heat wave, a national heat wave plan was put in place. This has four levels of alert, and provides in particular for communication actions aimed at reminding the “individual preventive actions to be implemented”: drink enough water, take shelter from the heat, do not intense physical exercise… In short, protect yourself as much as possible in order to avoid suffering from heat stroke which could be life-threatening.
The heat would peak in France on Saturday June 18, with a thermal anomaly of +10°C in the afternoon.
This heat wave could be as intense as that of July 2006, and the second most intense in June after that of 2019. pic.twitter.com/kBMHLXOp4o
— Gaétan Heymes (@GaetanHeymes) June 13, 2022
But concretely, how does the human body cope with these extreme heat conditions? Why are they so dangerous? Which of our organs are most affected by rising temperatures, and when do things go downhill?
Human body temperature usually fluctuates between 36 and 38°C. Within this range, biochemical reactions are able to take place normally, a sine qua non condition for the proper functioning of our cells and organs. To adapt to environmental changes that could take it out of this comfort zone, such as during a heat wave, the human body is well equipped.
Abnormal variations in body temperature trigger a physiological response in our body. This aims to bring our internal temperature back to more normal levels. This thermoregulation can be compared to a home thermostat: if the temperature deviates too much from the set temperature, the heating or air conditioning systems kick in to reach the desired temperature again.
In the human body, this thermostat is located at the base of the brain, in an area called the hypothalamus. This is where the information provided by temperature sensors located in our peripheral organs, such as skin or muscles, is integrated and processed, triggering a physiological response when needed.
Once Once the response is triggered, the first (and most important) physiological reaction is the production of sweat. By evaporating, it dissipates the heat, at the level of the skin and the extremities of the body (hands, feet).
This system is very effective at cooling the body, but may require up to 2 liters of water per hour in extreme heat. For this reason, as we will see later, during high temperatures, the body manages its water as efficiently as possible, recycling it as much as possible.
Nevertheless, to maintain the thermoregulation capacities of our body, it is essential to drink to refill the reservoir. If we do not drink enough, the risk is to run out of water, and therefore to lose the ability to sweat and cool off, which can lead to overheating of our organs. By drinking, we also absorb the electrolytes and salts needed to maintain blood pH and our cells to function properly.
From the brain to the kidneys
To understand what can go wrong in heat stroke, see how the thermoregulatory response affects the functioning of our various organs, and how these react to extreme temperatures.
The cardiovascular system is one of the first affected. In order to be able to sweat, the blood flow must move from the central organs to the peripheral organs so that it can cool there. One of the visible consequences is that people who suffer from the heat often blush. The loss of water through sweating and the redistribution of blood flow causes a drop in blood pressure. In an attempt to compensate, to maintain blood flow through vital organs, the heart beats faster.
If the redistribution of blood flow is accompanied by too much water loss, blood pressure drops dangerously, which can cause fainting, signs of heat stroke. If left untreated, this drop in blood pressure can lead, in the most severe cases, to heart failure.
The brain is another vital organ that suffers from stress in hot weather. The increase in temperature disrupts the communication between nerve cells and can even damage them or even cause their death. This is because heat affects the structure of DNA and proteins, as well as the integrity of cell membranes.
Natural climate control
Dehydration also causes electrolyte imbalances which can disrupt communication between nerve cells and muscle cells. The longer the overheating lasts, the more serious the consequences can be. Cognitive pathways can be dysregulated, which can cause emotional disturbances such as increased anxiety, headaches, impaired judgment, etc.
Remarkably, the brain is notably cooled by the respiratory system. When overheated, the body increases the rate of respiration, thereby cooling blood flowing to and from the brain through surface cooling and heat exchange mechanisms. This system can literally be considered natural air conditioning. It does, however, have a negative effect: it raises blood pH, due to lower CO2 pressure, which could endanger the cell functions of other organs.
Another important organ that receives less blood during hot weather due to its redistribution to the periphery of the body: the intestine. This loss interferes with its proper functioning and, in extreme cases, causes nausea and vomiting.
Finally, the loss of water and salts through perspiration also affects the urinary tract. Under the influence of a specific hormone produced by the brain (antidiuretic hormone), the reabsorption of water and salts is stimulated, in order to compensate for the loss of blood pressure in the cardiovascular system.
< p>Consequently, our kidneys produce less and less urine. This one is concentrated, which is manifested by its browner color. We go to the bathroom less often; when periods of high temperatures are prolonged and you are dehydrated, the kidney tissue can be damaged, and the kidneys no longer function properly.
A system that has its limits
The thermoregulatory system of our body is particularly well adapted, allowing us to cope with extreme heat conditions. In addition to the physiological response, heat triggers a behavioral response. When the temperature rises, our thirst increases and we tend to seek cooler and more comfortable places.
However, in the event of a heat wave, our body is subjected to intense stress, and its thermoregulation can reach its limits. A body temperature above 40°C pushes the system to its limits, and even beyond its capacity for self-healing. In this case, the risk of loss of control of temperature regulation is real, which can compromise the functioning of the organs.
The most vulnerable organ in this respect is probably the brain. The heatstroke and accompanying dehydration cause a systemic inflammatory reaction which, in turn, leads to irreversible brain damage, which can lead to death if action is not taken very quickly.
Listen his organism
< p>People who don't listen to their bodies, don't drink water and neglect the advice given by health authorities in times of heat wave bring their body to the limits of human physiology. They risk exhaustion or heatstroke, which can have potentially fatal consequences in the event of multiple organ failure.
The same goes for people at risk like the elderly and patients with a history of cardiovascular disease. Also, older people may be less aware of the dangers of heat because their body heat sensors work less well than those of younger people.
Babies and toddlers, on the other hand, depend on the vigilance of their parents, who must be careful to take the necessary measures to protect them.
Finally, it is important to limit the consumption of drinks containing alcohol or caffeine, because these substances themselves have dehydrating effects.
In the end, the advice to remember is simple: drink water, cool off from time to time, avoid the highest temperatures, and follow the recommendations authorities. And, of course, also caring for those who are most vulnerable during these exceptional episodes.