Why can t people breathe in water?

Have you ever found that those who breathe with gills or with ** are cold-blooded animals (tuna is homeothermic, which is a special case). Mammals living in the ocean, such as whales and dolphins, all breathe with their lungs, and a big reason is that we are homeotherms, in order to maintain body temperature, the oxygen consumed per unit time is very large, and the oxygen content in the water per unit volume is much lower than that in the air, that is to say, to obtain the same amount of oxygen, it is necessary to breathe at a faster frequency or evolve a larger specific surface area"Alveoli"。There is a big logical hole in my previous statement, and it should not be started from the partial pressure of oxygen in the air and the concentration of oxygen in the water) I think the main problem is that the structure of the respiratory organs of humans and fish is different.

The gills of the fish's respiratory organs are open, completely immersed in water, and the bony fish continuously flows the water with high oxygen content through the gills through the opening and closing of the mouth and gill cover, and some cartilaginous fish, such as sharks, are achieved by constantly swimming to make the gills and water produce relative flow, which is actually the convective mass transfer in the "Principles of Chemical Engineering". The human lungs are almost completely closed, only the relatively narrow respiratory tract is connected to the outside world, and the gas exchange place is at the end of the respiratory tract - alveoli, although the total exchange area is huge, about 80 square meters, even if all immersed in water, water can not flow effectively around the alveoli, oxygen is intermittent static diffusion, and the diffusion rate of oxygen in water is 1/10,000 in the air, which means that taking a deep sip of water, holding for one second and holding for 3 seconds The effect difference is not large, and the utilization rate of oxygen in water is not high for each breath, What's worse is that the concentration of oxygen in water is one-twentieth that of air. In fact, if you open the gill cover of the fish and prevent it from swimming and put it into the water, you will definitely suffocate to death.

Fish can adapt to underwater breathing, and I think there are three main points: first, oxygen diffuses into the bloodstream in a continuous convection manner; Second, the venous blood oxygen concentration of fish is low, which increases the driving force of oxygen diffusion; Third, the hemoglobin of fish has a strong ability to bind oxygen. And the reason why people can't do it can be seated in the right number.

Anyway, the so-called drowning, it must be hypoxic suffocation and brain death, in fact, deep-sea diving will choose to replace oxygen with oxygen-rich liquid, not to mention the specifics, anyway, if the water (liquid) can dissolve enough concentration of oxygen, of course people can breathe in the water (liquid)! Fish breathe with gills. In fact, fish, like people, must breathe oxygen to survive, there is oxygen in the air and water, and the human lungs can separate the oxygen in the air but cannot absorb the oxygen in the water, so people can only live on land and cannot breathe in the water, most fish have no lungs but have gills, and the gills of the fish can separate the oxygen from the water.

Human beings need oxygen to breathe, and there is indeed oxygen in water, although it is only one-fifth of the oxygen content of air. But people are different from fish, people breathe with their lungs, and fish breathe with touch...The human lungs can only absorb air.

If special means are taken to dissolve enough oxygen in the water, the lungs can obtain enough oxygen in the water, that is, they can breathe in water by absorbing water for a period of time, but the water dissolves carbon dioxide less, and cannot bring out the carbon dioxide in the blood, and eventually suffocates with the increase of carbon dioxide in the blood, which is of course very painful.

If you use perfluorocarbon liquid, it is not the same, it has a high solubility of oxygen and carbon dioxide, and people can't drown in perfluorocarbons, but this set of lungs specially designed for air does not work so smoothly for liquids, and the oxygen exchanged by perfluorocarbons may not be sufficient, but it will not drown.

Web linkDogs can survive for half an hour in oxygen-rich water.

The web links to reports on perfluorocarbons.

People can't breathe in the water, and the water will definitely get into the eyes.

The human respiratory organ is the lungs, and the lungs can only absorb oxygen from the air, so sometimes people choke when they drink water, that is, they are still breathing while drinking water. Therefore, people cannot breathe in the water, cannot exchange water and oxygen, and cannot survive underwater. Fish breathe with gills, and their gills can absorb oxygen from the water, and they can exchange nutrients for water, so they can survive underwater.

Similarly, because the gills of the fish cannot draw oxygen from the vigills, which are filled with capillaries, the capillaries can exchange gases, and when the fish swallows a mouthful of water, the food is eaten, and the water is expelled from the posterior edge of the gill cover. When water flows through the gills under the gill cover, the capillaries begin to exchange gases, i.e. carbon dioxide is excreted into the water, and oxygen enters the capillaries and participates in the blood circulation. Therefore, the larger the contact area with water, the more oxygen passes.

On the shore, the gills are brought together, the surface area is reduced, and gas exchange is not well carried out, which is one of the reasons.

In fact, the main reason is that the fish cannot obtain the oxygen that is insoluble in the water, so the fish cannot get enough oxygen on the shore and eventually die of lack of oxygen. In the same way, animals on land, including humans, breathe with their lungs, and the lungs can only exchange gases with the air on land.

The second problem is that water must enter the eye, because water is pervasive. Therefore, when diving, you will always wear diving goggles. If you don't bring it, you will feel uncomfortable when you just open your eyes in the water, and if you open your eyes in the water for a long time, it will also cause your eyes to be red and swollen because of bacterial infection.

So try not to keep your eyes open in the water.

You can't breathe at the bottom of the water, and the Gillis record should be dozens of minutes, and you can dive to dozens of meters underwater, depending on your lung capacity; At present, watching cartoons, there are two situations in which you can breathe underwater, one is to have Doraemon, the other is to have a submarine, which can breathe underwater, or there is diving equipment, or there is a tunnel by the sea, an underwater world or an undersea restaurant, in other cases, you can rely on your own fantasy, not to mention underwater, space is possible, anyway, I am a person who holds back for half a minute, and living well is the last word.

Mermaids can, but humans cannot, because people don't have gills like fish, and they can take in oxygen dissolved in water, and people rely on their lungs to absorb oxygen in the air. So man can't live in water like a fish. Aquatic animals can directly exchange dissolved oxygen in water, and gills do this, while human lungs can only exchange with gaseous oxygen, and can only breathe gaseous oxygen, and isolating the air underwater will naturally suffocate.

No. Some people who have been trained can maintain their life activity underwater by lowering their heartbeat and reducing their oxygen consumption. But when it comes to not breathing underwater.

Fish, like people, have to breathe oxygen to survive, and there is oxygen in the air and water, and the lungs of humans can separate oxygen from the air but they can't absorb oxygen from the water, so people can only live on land, but they can't breathe in the water, and most fish don't have lungs, but they have gills, and the gills of fish can separate oxygen from the water, so there are some fish, in addition to gills, and lungs, so those fish can live on land for a while, some of them can only live for a few hours, and some of them can live for a few days Others can even live on land for a few years.

Humans cannot breathe underwater because human lungs do not have a large enough surface area to absorb enough oxygen from the water, and the internal structure of the human lungs is better suited to handle air than water. However, humans have tried to breathe in other liquids, such as fluorocarbons. Fluorocarbons dissolve enough oxygen so that the lungs can absorb it out.

Humans can usually hold their breath in the water for less than 2 minutes, and after systematic training, the time of holding their breath in the water may be extended.

As evidenced by the Guinness Book of World Records, the longest underwater breath-holding time for a human can reach 22 minutes and 2 seconds, is done by a Danish physician.

In addition, the duration of breath-holding will also be determined by the physical condition of the day and the amount of exercise underwater, the greater the amount of exercise, the greater the oxygen consumption, and the shorter the breath-holding time.

Note: People are not allowed to breathe underwater, but they can hold their breath underwater to consume oxygen in their lungs.

Can people breathe freely under the pool and their clothes won't get wet? After reading it, I realized that I had been deceived.

People can't breathe underwater, and they need equipment to breathe underwater.

No, you can't. Unless there is an outside oxygen cylinder.

People rely on their lungs to absorb oxygen from the air. So man can't live in water like a fish. Aquatic animals can directly exchange dissolved oxygen in water, and the gills do this, while the human lungs can only exchange with gaseous oxygen, and can only breathe gaseous oxygen, isolating the air underwater and exhaling naturally.

Humans cannot breathe under the water because their lungs do not have the ability to absorb oxygen from the water.

Humans did not evolve directly from fish, but gradually evolved over millions of years. While there are commonalities and connections between the two, they also have a lot of differences.

In the process of evolution, our ancestors gradually adapted from the marine environment to the terrestrial environment, and the appearance of hair on the body surface and the ability to walk with two feet to support the body.

At the same time, the human respiratory system has also changed, from the gill organs to the lungs, so that humans cannot breathe in the water. This is due to the fact that the two organisms have adopted different adaptation strategies over the course of their long-term evolution, resulting in different physiological structures and functions.

In addition, even though humans cannot breathe in the water, we can still stay in the water for a period of time with diving equipment and techniques, perform activities such as deep diving. The development of these technologies and equipment allows us to better explore and use underwater resources.

Behavioral characteristics of people

First, man is a possibility of existence. The essence of human beings is constantly generated in their own activities, and it is a kind of "self-regulation".

Second, people are autonomous and creative. People not only learn, but also ask questions, explore, and innovate.

Third, human beings have the essence of development. The practical nature of human beings determines that human beings can continuously carry out self-denial, self-transcendence, and self-realization through conscious and purposeful independent creative activities, that is, human beings have the essence of development.

Fourth, human beings are historical and realistic. There are two meanings: one is that the essence of human self is gradually generated in the constantly developing history and real life, and people always live in the specific historical and real space.

Second, the formation and development of man's self-essence must be constrained by certain historical and practical conditions.