People and Oxygen: How Much Oxygen Do Humans Need?
- There are only two mice and myself in the world who can enjoy the pleasure of this gas - Joseph Priestley
On August 1, 1774, Joseph Priestley who was a priest and now a chemist used a convex lens to concentrate sunlight on mercury oxide, and obtained mercury and a gas. He carried out "exhaustive" experiments on this gas using the research methods at the time, and boldly inhaled this gas into his lungs with a glass tube, and then recorded his feelings:
"I feel very happy. My lungs feel the same as breathing air, and there is no discomfort. Moreover, after inhaling this gas, my body is still very relaxed and happy for a long time. Maybe, one day, who can judge this kind of gas. Gas won't become a fashionable luxury? But there are only two mice and myself in the world who can enjoy it."
Now we all know that this gas is oxygen - an essential element for life - but Priestley was a die-hard supporter of the prevailing "phlogiston theory" and a diehard fan of the "air is a single element" theory. With a stroke of his pen, he named the most important discovery of his life "dephlogiston air".
Antoine Lavoisier, who became an academician of the French Academy of Sciences at the age of 25, did not believe in this evil. He successfully produced "dephlogiston air" by repeating Priestley's experiment, and then after repeated experiments and in-depth thinking, 3 years later , he officially named this gas Oxygen (oxygen), and proposed the famous "oxidation theory", which overturned the "phlogiston theory" that had plagued the chemical industry for hundreds of years and put the direction of chemical research back on the right track. .
Due to Lavoisier's great achievements, although he was not the first person to discover oxygen, the great teacher Engels still rated him as "the person who really discovered oxygen". When it touches the tip of the nose, there is still no truth."
- People can go without water for 2 days and without food for 7 days, but they can't live without oxygen for a moment - my physiology teacher
A major reason humans are highly intolerant to hypoxia is our developed brains. Our small cranial cavity is crowded with more than 80 billion neurons. These neurons communicate with each other through axons and dendrites, forming the most complex and sophisticated existence on this earth, and allowing us humans to stand at the top of the food chain.
These brain neurons are constantly running, constantly controlling and adjusting our thoughts, words and actions, consuming 20% of the blood oxygen supply with 2% of the body weight; because the space in the skull is extremely precious, it is not allowed at all. Too much blood is kept in reserve, so the blood oxygen reserve of the brain is extremely low. This leads to the irreversible death of neurons in the brain once the blood supply is completely terminated for 3-5 minutes; it only takes a few tens of seconds to cut off the blood flow, and the brain will collapse and faint.