Diving is a scientific nitrogen
In addition to the GF problem mentioned in the first column, one of the most frequently asked questions is why nitrogen is drunk. Or, why the higher the solubility of gas in fat, the stronger the anaesthetic. This form has also appeared in the previous article on hernia:
The first thing to note is that the relationship between fat-soluble and narcotic is just a phenomenon observed in anesthesia medicine. In 1899 and 1901, Meyer and Overton independently published papers and found that if the various substances are described in terms of fat solubility (represented here as solubility in olive oil) and narcotics (here represented at the required minimum concentration, the required concentration The higher the narcotic, the lower the narcotics is. Draw a map. The results are as follows:
From the map, the correlation is very strong, that the anesthesia must be caused by fat solution?
In this era of "big data statistical analysis," remember that the first article in "One hundred strokes of statistical deception" is to introduce causality with relevance.
Baidu has recently come to a conclusion based on the relevance of search records: People who go to low-end foot massage shops go to hospitals more often than those who go to high-end ones. Therefore, to go to the low-end foot spa can better promote physical health, medical insurance costs should also be reduced accordingly, you say is not it?
- Where is this special place and where?
Therefore, the fact that "high fat-solubility leads to high anaesthesia" is not a definitive conclusion. We do not know what the principle behind the above diagram is.
Scientific research in the field of diving generally, because the usefulness is not so great, the financial support that can be obtained is also less, the military and commercial diving company's research is limited to their own most interested direction, but also pay more attention to practicality, for the mechanism There is relatively little research. Fortunately, anesthesia has a wide range of important uses in medicine, so academic research on the mechanism of anesthesia is quite rich.
You guess what their conclusions are?
The answer is that there is still no conclusion.
However, there are some hypotheses that are more widely accepted and supported by certain experimental data. A British technical diving instructor with a Ph.D. degree often mentions "fat-soluble", "neural conduction", "myelin sheath", and "anesthesia" in theoretical classes.... When you meet a serious student, my WeChat will start to flash. : Tofu bean curd, why the higher the fat solubility, the more it will affect the nervous system?
The first misunderstanding here lies in the "fat" character of "fat-soluble". It does not mean "fat" but "lipids". Lipids are a large class of molecules in the human body. All cell membranes, including the membranes of nerve cells, are composed of two lipid molecules. Lipid molecules are pro-hydrophilic and hydrophobic. In short, they are like water molecules and they don't like water molecules. So in a human body with a water content as high as 60%, the lipid molecules of the two layers are automatically arranged in the following way: Like the water molecule on the other side, do not like the water molecules on the inside.
The most popular hypothesis at present is that fat-soluble substances are more likely to enter the cell membrane interior. After the gas molecules enter the nerve cell membrane, it will lead to changes in the structure of the cell membrane, thereby affecting the transmission of nerve signals, causing anesthetic effects such as slow response. (Classmates who are not interested in nerve conduction can click here to exit when they see this.)
Why does the change in cell membrane structure affect nerve signaling? Because the transmission of nerve signals is achieved through the "action potential", that is, the change in the potential difference between the inside and outside of the cell membrane. In the resting state, the potential difference between the inner and outer neuronal membranes is -70mV, and the highest potential difference of the action potential is +50mV - these data are indeed obtained by electrophysiologists through continuous experiments and measurements.
The generation, maintenance, and transmission of this change in potential difference require that some proteins called “ion channels†on the cell membrane carry positive and negative potassium and sodium ions into and out of the cell; they also need a layer of material called myelin sheath outside the nerve cell. These ions are confined to a small area outside the cell membrane so as not to fall into the ocean of the human body. There is a disease called MLS. It is because the destruction of nerve myelin causes the transmission of nerve signals to fail. The patient will gradually lose the function of various parts of the body. It is really miserable to think about it.
Before the mainstream theory, gas molecules entered the cell membrane, resulting in an increase in membrane volume, ion channel compression, loss of normal switch function, thus loss of nerve conduction capacity, resulting in slow response and other anesthetic effects. However, the latest research suggests that gas molecules may not simply enter the cell membrane and cause morphological changes. It is likely that the gas molecules directly interact with ion channel proteins and affect their function.
In short, there is still no conclusion.
Even if you have the patience to see this last, most of them are already hazy. But it doesn't matter. You just have to remember one thing: Why is nitrogen so drunk? There is only hypothesis in the world so far and there is no conclusion.
"You didn't know anything when you talked for a long time, but you really meant science?"
I think this is the biggest misunderstanding of science for the public. Its core is not knowledge but a scientific attitude. We are only trying to find out the principles behind the various phenomena (ie, knowledge) in a way that we can come up with. Even if the new knowledge or evidence emerges from the knowledge we seek, it can also be overturned or amended. Can be falsified, that is, the biggest difference between science and religion.
Diving is a science because there are too many interesting phenomena to study. Maybe we don't understand it yet, but we may understand it in the future. Even if you do not fully understand it, you can also seek out the laws and then verify it in practice. This process of continuous inquiry is really the most interesting thing in the world. The freshness and stimulation are endless.
So, don't ask me why I didn’t resign to open a dive shop—I really love science.
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