Final answer:
Humans inhale air with about 20.9% oxygen, use approximately 5% of it, and exhale around 15% oxygen alongside carbon dioxide. Inhaled oxygen is used for energy production in cells, resulting in CO₂ as a waste product. This gas exchange system is vital for bodily functions and maintaining pH balance.
Step-by-step explanation:
The air we breathe contains approximately 20.9% oxygen, but not all of this is used by the body. On average, humans use about 5% of the oxygen they inhale and exhale around 15% as part of the exhaled air, which means they breathe out most of the oxygen they inhale along with carbon dioxide and other gases. Inhaled oxygen crosses the lung tissue, enters the bloodstream, and is transported to the organs and tissues, where it is critical for the metabolic processes that produce ATP (Adenosine Triphosphate).
Oxygen metabolism in the cells results in the production of carbon dioxide (CO₂) which is a waste product that must be removed from the body. Exhaled air consists of a mix of nitrogen, oxygen, water vapor, and a higher concentration of carbon dioxide than was originally inhaled. This exchange process is efficiently managed by the respiratory system and is crucial for maintaining the body's pH balance as well as preventing the accumulation of toxic levels of CO₂.