The human brain detects extreme heat or cold in a similar way that leads to excessive pain
When we touch something very hot, or very cold, our senses translate this into a feeling of pain. Why is this happening, and what is the scientific reason behind this feeling of pain?
On the surface, there don’t seem to be many similarities between an ice cube and a hot waffle baking machine. Despite that, they both have the ability to sense pain if someone touches or comes close to either of them.
Extreme heat and extreme cold would cause an unpleasant shock to the skin, as it was found that the brain detects these two effects, which express extreme heat extremes, in similar ways.
Among these senses, of course, is the sense of touch itself, or the ability to feel through the skin, and what are known as mechanical stimuli. There is also a sense of “proprioception”, which relates to the ability to recognize the direction and position of the body.
In addition, there is what is known in medical science as “pain sense”, which is the body’s ability to recognize stimuli and stimuli that are harmful, or those that are likely to harm it.
The sensation of pain is the body’s reaction to the sensation of such stimuli.
This “sense of pain” leads us to try to stay away from any stimulus that causes us pain; Whether this stimulus or stimulus is of a mechanical, chemical or thermal nature.
If you put your hand in the fire, the resulting burning sensation will cause your body to remove your hand as quickly as possible. In fact, feeling pain is proof that your body is working hard to keep you safe. So, losing the ability to do so means that you are in real trouble.
Our reaction to the sensation of something cold is entirely due to a specific protein in our bodies
The basic principle here is that sensory neurons extending throughout the body have “a set of channels that are directly activated by temperature, whether it is hot or cold,” says Jörg Grandel, a professor of neurology at Duke University in the United States.
Through a study of genetically modified mice, over the past 15 years, scientists were able to prove that these channels – which are proteins embedded in the walls of nerve cells – are directly involved in the issue of sensation of heat.
Among the most common of these are sensory receptors, the role of which scientists understand more than others; A receptor known as TRPV1 is responsible for the sensation of intense heat.
Normally, a temperature would need to reach 42°C (107.6°F) to activate this receptor, a temperature that humans and mice alike would normally consider excruciatingly hot.
Once the skin reaches this level of sensation, that nerve channel becomes active, which in turn activates the entire nerve, and a signal is transmitted to the brain with a very simple message, which appears in the form of a “scream” of pain.
In principle, Grandel adds, the same mechanism works in relation to the sensation of cold. But the protein in question here is called TRPM8, and it not only activates when cold temperatures are reached, but it activates if the human body is exposed to moderate cold, not painfully frigid.
Here remains a third protein, called TRPA1, which is perhaps the most mysterious of the proteins in this category for scientists. While they discovered that this protein becomes activated by intensely cold stimuli, it is not clear whether it is actually involved in monitoring such stimuli.
Taken together, these three proteins enable human skin to detect a wide range of temperatures and the body to act appropriately in response.
The role of these proteins, as pain receptors, is to help humans avoid certain temperatures. Therefore, mice with abnormalities in TRPM8 receptors no longer avoid cold temperatures. Which means that these mice (and we probably do too) don’t make an effort to enjoy cool temperatures that are pleasant to them. Instead, these rodents work hard to avoid extreme heat or cold, which explains why they prefer temperate, warm environments.
Although the researchers determined the levels of temperature that lead to the activation of these proteins, this does not negate the possibility of modifications or changes in them.
And if your skin gets burned by exposure to intense sunlight, the lukewarm shower water may feel unbearably hot.
It turns out that this is because inflammation in the skin makes the receptor known as TRPV1 sensitive, which leads to a decrease in the level of heat needed to activate this receptor, prompting it to send a signal to the brain to feel pain.
But temperatures are not the only stimuli that lead to the activation of receptors such as these, plants produce this effect as well. It may be surprising to learn that the protein TRPV1, which is activated by intense heat, is also activated if it is exposed to capsaicin, the compound that gives chili peppers their scorching taste.
TRPM8 is also stimulated by the refreshing effect of menthol, a chemical found in mint leaves. TRPA1 is also known as the “wasabi receptor” – in reference to the wasabi plant known as Japanese radish – because it is activated by exposure to harmful compounds found in the mustard plant, which belongs to the same family.
But why have plants evolved chemicals that activate receptors that are also activated by exposure to certain temperatures?
Here, Ajay Dhaka, a professor of molecular biology at the University of Washington, says that some plants may have evolved chemicals such as capsaicin to prevent certain organisms from devouring them, or to make those organisms leave them alone, while remaining an easy prey for other creatures.
Dhaka points out in this context that the substance does not stimulate the receptor known as “TRPV1” in organisms such as fish, birds or rabbits, while affecting the same receptor in humans and rodents. The same theory seems to apply to the reasons for the development of other substances such as menthol and mustard.
In other words, this eccentric relationship between plants and temperature may reveal a lot about the evolutionary history of plants as well.
Perhaps, by chance, these plants found a way to “hack” the capabilities inherent in our bodies, in terms of monitoring the different levels of heat we are exposed to, and then develop components capable of activating the same receptors responsible for this, so that when we are exposed to those components, we feel pain. Similar to what we suffer if we are exposed to extreme heat or freezing cold.
Therefore, our perspiration when eating a snack containing jalapeno peppers is not caused by any characteristic inherent in this type of pepper per se, but rather results only from the fact that capsaicin and the intense heat have the ability to It can stimulate the nerves in the skin – and thus the entire body – in one way.
By utilizing a receptor originally configured to react to irritating and harmful stimuli, these plants have found a roundabout way to avoid being devoured by humans in large quantities and too quickly.
At least that was until we found a way to enjoy the excruciatingly burning taste of spicy foods and the teary-eyed flavor of wasabi.
So, the next time you devour a plate full of pepper, and feel your heart beat faster; You have to take a moment to think about the possibility that this feeling was caused by an evolutionary battle that took place over millions of years between plants and animals. It is a battle in which we seem to be winning, at least for the time being.