Why cant we breathe under water? Why do we die if we drown in water even though water has oxygen?

Answer 1

that's life...

Answer 2

Our pulmonary alveoli (the microscopic air cells at the end of the airways) can diffuse oxygen from the inhaled air to the blood and carbon dioxide on the opposite path. But they are not able to do the same if oxygen is in solution in the water. There is another thing to be said: when a man is drown in the sea water, the high concentration of salt in the inhaled water causes (because of osmosis) dehydratation of the interstitial substance of lungs, increased volume of alveoli and constriction of the airways; instead, when not salted water is inhaled, the osmosis causes on the contrary a pulmonary oedema and ARDS which can cause death.

Answer 3

Lungs aren't designed for it. Aquatic animals have a much lower metabolic rate, so they don't need as much oxygen. They are streamlined and nearly weightless, so motion requires very little effort. Whales and dolphins breathe air, but they don't need to do it often. The average human lung capacity is about 5 liters, with each normal breath moving about half a liter. You would need 25 liters of oxygen-saturated water to get as much oxygen as a liter of air.

Answer 4

Our lungs evolved to extract oxygen from the air, which contains about 20% oxygen. Water only contains a fraction of a percent of oxygen, so fishes' gills have to work hard to extract the oxygen from water. Lungs work in an air-to-blood environment, wheras gills work in a fluid-to-blood environment. If our lungs fill with fluid, it blocks the flow of air, and we drown.

Answer 5

Marine animals have specialised gills that extract oxygen from water as it passes through them. Our lungs take in air that has oxygen, nitrogen argon, co2 etc. The air is then exposed to alveoli that are very thin, there haemoglobin in blood takes oxygen with it, and the rest is resent out. So when water blocks the alveoli we die.

Answer 6

Because we have evolved to filter air.

Technically, drowning is suffocation. When we are under water and cannot get air, our bodies will not allow water to enter the lungs. It's simple survival instinct; if it did, it would block our process of extracting oxygen from air, and we would suffocate. It's only after consciousness is lost that the lungs begin to fill with water, and only after death that they fill completely.

Also, it's chemically impossible. Water is dynamic; it's constantly changing from H20 to H30(+) + 0H(-) and back again. Hydronium (H30) is very acidic and the ratio of hydronium to hydroxide is what gives water it's Ph. Our bodies are simply not meant to handle this chemical reaction occurring in our lungs.

Answer 7

Humans cannot breathe underwater because our lungs do not have enough surface area to absorb enough oxygen from water, and the lining in our lungs is adapted to handle air rather than water...

however there are ongoing experiments using oxgen rich fluorocarbon liquids, if successful this technology could be used in a variety of areas from deep see diving, medicine and even space travel.

http://en.wikipedia.org/wiki/Liquid_breathing <-- very interesting stuff

Answer 8

Because your lungs are not made to deal with water.

People drown when too much water gets into their lungs. When that happens, the lungs can't carry enough oxygen to the brain and the rest of the body.

Answer 9

because our lungs are made to filter air not water... they can not extract the O2 from the liquids

Answer 10

no gills fish boy "there's your best answer chosen by voters "help me out guy's