Final answer:
While our bodies cannot use atmospheric nitrogen directly due to its unreactive nature, nitrogen is essential for synthesizing proteins and DNA/RNA.
Nitrogen is made available through the food chain via the process of nitrogen fixation. Additionally, atmospheric pressure helps maintain dissolved nitrogen in bodily fluids.
Step-by-step explanation:
The nitrogen in the air is essential for our bodies, although indirectly. Most organisms, including humans, cannot use the abundant atmospheric nitrogen (N₂) directly because of the strong nitrogen-nitrogen triple bond which makes the N₂ molecules unreactive.
However, nitrogen is a vital element as it is a component of proteins and the genetic material (DNA/RNA) of all plants and animals.
In the human body, nitrogen is mainly used after it has been fixed by certain bacteria and converted to a more reactive form through the process of nitrogen fixation.
This reactive nitrogen is then taken up by plants and incorporated into plant proteins. When we consume plant or animal matter, we get the nitrogen we require to synthesize our own proteins and nucleic acids.
Atmospheric pressure is important as it helps to keep the gases, such as nitrogen, dissolved in body fluids. This is crucial for maintaining physiological processes.
Moreover, human activity can impact the nitrogen cycle significantly through the combustion of fossil fuels and the use of fertilizers, which may lead to environmental issues such as eutrophication and climate change.