Oxygen: What is oxygen – and can you get too much of it?

You are constantly surrounded by oxygen and your cells burn the element 24 hours a day. But what do you really know about this significant gas of life?

You are constantly surrounded by oxygen and your cells burn the element 24 hours a day. But what do you really know about this significant gas of life?

What is oxygen?

Oxygen is the third most abundant element in the universe after hydrogen and helium. It is element number eight in the periodic table and therefore has eight protons in its nucleus and eight electrons orbiting it.

When two oxygen atoms fuse together, they form the oxygen molecule O 2 – a colorless and odorless gas on which all evolved life relies.

However, three oxygen atoms can also bond to form O3 – ozone. Near the Earth’s surface, ozone is a toxic greenhouse gas, but higher in the atmosphere, ozone forms the ozone layer, which slows down cancer-causing ultraviolet radiation from the sun.

An oxygen atom consists of eight protons in the nucleus and eight electrons orbiting it. Therefore, the element has the number 8 in the periodic table.

What do the cells do with the oxygen?

Advanced multicellular organisms have developed oxygen in order to survive, because oxygen is crucial in the energy production of the cells and thus of the whole body. In fact, this takes place in energy granules, which are a kind of energy center of the cells and produce the substance adenosine triphosphate, ATP.

The formation of ATP from the sugar glucose occurs in many steps where oxygen is involved – for example, when the substance pyruvate is oxidized by absorbing oxygen.

Glucose can also be broken down without oxygen, but when oxygen is present, the process is thirteen times more efficient for the organism.

Thus, oxygen is absolutely necessary to be able to form larger organisms such as snakes, humans and dinosaurs.

The mitochondria are also called the powerhouse of the cells. Here, oxygen is used to burn the sugar glucose so that the energy molecule ATP is formed.

How much oxygen is in the air?

Dry air at one air weight contains 20.95% oxygen. If the air is humid, the volume decreases because part of the volume goes into water vapor.

The amount of oxygen has varied throughout Earth’s history. For the first two billion years, the air contained no oxygen, but by 2.4 billion years ago, its amount began to gradually increase.

During the period after multicellular organisms emerged on Earth more than 240 million years ago, the oxygen content in the atmosphere has varied between 15 and a whopping 35%.

The amount of oxygen was the highest during the coal era and was probably the driving force behind the giant insects of that time – including dragonflies that had a 70 cm wingspan.

The Earth’s atmosphere consists of almost 21 percent oxygen, just over 78 percent nitrogen, 0.038 percent carbon dioxide and 0.93 percent argon.

How much oxygen does a person use?

We breathe an average of 16 times a minute when we are active, but not under a lot of stress like during a long run. With the breath, a fully grown person reaches about 500 liters or 0.7 kg of pure oxygen daily.

We don’t use all that oxygen we draw down into our lungs at all. When the air is breathed in, it contains about 20 to 21% oxygen, while the oxygen content is about 15% when the air is breathed out again.

The oxygen is also not evenly distributed inside the body. Your brain, which is only about 2% of your body weight, requires about a fifth of all the oxygen it needs to handle its enormous energy needs.

We inhale approx. 2000 liters of oxygen per day, but we only use about a quarter of it. Therefore, there are approx. 15 percent oxygen in our exhaled air.

What happens if you get too much oxygen?

Too large a dose of oxygen is initially harmless, but if a person is exposed to too much for more than 24 hours, it can damage cells in the lungs.

Pure oxygen, i.e. air consisting of 100% oxygen, is used, among other things, in hospitals in the treatment of patients with smoke poisoning or cardiac arrest.

In fact, the Apollo astronauts breathed pure oxygen throughout their journey to the moon, but at a lower atmospheric pressure than at the Earth’s surface.

Namely, it is not the percentage of oxygen in the lungs that damages the cells, but the so-called relative pressure, which refers to how much of the pressure of the air against the lung tissue is oxygen.

Pure oxygen is used in hospitals, including for cardiac arrest and smoke poisoning. There, the oxygen breathes new life into the cells.

How does oxygen get into water?

Oxygen in the sea comes partly from the atmosphere, partly from the photosynthesis of green algae and other organisms, which together produce as much oxygen as plants on land.

The oceans have a very stable stratification where the water masses mix very little oxygen with each other.

Oxygen from the upper water layers therefore does not reach the deep ocean, which instead receives its oxygen from ocean currents, where oxygen-rich surface water in some places sinks many kilometers down and is separated. This happens, for example, in the sea between Iceland, Greenland and the Faroe Islands.

This uneven distribution means that the bottom areas in some places, for example in the northern part of the Indian Ocean, are almost devoid of oxygen.

According to scientists’ calculations, 50-80 percent of the Earth’s oxygen production comes from plankton, algae and water bacteria.

Does oxygen cause diving sickness?

It is not oxygen but nitrogen that creates air bubbles in the blood and causes diver’s sickness if you ascend too quickly after a deep dive. The blisters can act like blood clots and in the worst case, lead to death.

In the treatment of diving sickness, the diver needs to be put under more pressure, usually in a pressure chamber, so that the air bubbles dissolve again. Often these unfortunate divers breathe air with extra oxygen during the treatment.

However, diving sickness due to oxygen bubbles in the blood can theoretically harm professional divers who have unusually high levels of oxygen in their oxygen tanks. However, the body uses up oxygen so quickly that there is hardly any danger in doing so.

The cause of diving sickness is due to nitrogen bubbles in the blood and not oxygen poisoning.

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