Gasses We Breathe In and Breathe Out | Composition of Air

The gases we breathe in and breathe out do not only include oxygen and carbon dioxide respectively rather they include many more gases that compose the air. When we breathe, the air inhaled contains around 79% nitrogen, 21% oxygen, 0.03% carbon dioxide, and other gases.

However, only oxygen is absorbed by the blood and taken to the body parts. When we breathe out, the exhaled air contains 16.4% oxygen, 4.4 % carbon dioxide, 79% nitrogen, and the rest water vapour. In this article, we will study the composition of air- the inhaled and exhaled air, the gases we breathe in, the gases we breathe out, and how respiratory health is related to the gases.

Composition of Air

Air in the atmosphere is composed of nitrogen, oxygen, and different trace gases in addition to particles or aerosols due to various human activities and natural phenomena. The trace gases include carbon dioxide, argon, neon, helium, methane, krypton, and water vapour.

Composition of Inhaled Air and Exhaled Air

Except for the amount of carbon dioxide and oxygen, the composition of air that is inhaled and exhaled is nearly identical. The following table highlights their percentages:

Substance	Inhaled Air %	Exhaled Air %
Nitrogen	78.0	78.0
Oxygen	21.0	16
Argon	0.9	0.9
Carbon Dioxide	0.0390	4.0
Water Vapour	variable	variable

Gases We Breathe In

In the process of inhalation, the diaphragm contracts and moves downward. This leads to an increase in the space of the chest cavity, and the lungs expand into it. The muscles between the ribs, known as intercostal muscles, also help in the enlargement of the chest cavity. They contract to pull the rib cage both upward and outward during inhalation. As the lungs expand, air is sucked in through the nose or mouth.

The air travels down through the trachea or windpipe into the lungs. Coming through the bronchial tubes, the air reaches the alveoli, or air sacs. The composition of inhaled air is approximately 79% nitrogen, 21% oxygen, 0.04% carbon dioxide, water vapour in variable amounts, and trace gases in very low percentages.

Oxygen and Cellular Respiration

Once inside the lungs, oxygen undergoes a series of processes to facilitate its exchange with carbon dioxide. The air passages divide into smaller tubes, ultimately reaching tiny air sacs called alveoli. These structures are surrounded by an extensive network of blood vessels. The thin walls of the alveoli allow for the diffusion of oxygen from the air into the bloodstream, binding to hemoglobin in red blood cells.

Mechanism of Breathing

The movement of air into and out of the lungs happens due to the difference in the pressure gradient between the lungs and the atmosphere. Inhalation occurs when the pressure within the lungs is less than the atmospheric pressure, i.e., there is a negative pressure inside the lungs with respect to the atmospheric pressure. In the same way, exhalation occurs when the pressure in the lungs is higher than the atmospheric pressure. The diaphragm and the intercostal muscles help in the generation of such gradients.

Cellular Respiration

Within cells, oxygen plays a crucial role in cellular respiration – the process by which cells generate energy. Oxygen participates in the electron transport chain, facilitating the production of adenosine triphosphate (ATP), the cell’s primary energy currency. As cells utilize oxygen, they produce carbon dioxide as a byproduct.

Gases We Breathe Out

During the process of exhalation, the diaphragm and intercostal muscles relax which reduces the space in the chest cavity. As the chest cavity becomes smaller, the lungs deflate, which can be related to the release of air from a balloon. Due to this carbon dioxide-rich air flows out of the lungs through the windpipe and finally gets out of the nose or mouth.

The composition of exhaled air is approximately 79% nitrogen, 16% oxygen, 4% carbon dioxide, saturated with water vapor, and trace gases in the same percentages as were inhaled.

Carbon Dioxide and Gas Exchange

Carbon dioxide, though often considered a waste product, plays a crucial role in maintaining the body’s acid-base balance. Excess carbon dioxide is transported back to the lungs via the bloodstream. In the lungs, it is released into the alveoli and then expelled during exhalation. This process ensures that the pH of the blood remains within a narrow and optimal range, preventing acidosis or alkalosis, which can have detrimental effects on cellular function.

Gases and Respiratory Health

Environmental factors such as air quality, pollution, and altitude can significantly impact the respiratory system. Exposure to pollutants can irritate the airways and lead to respiratory disorders. Additionally, at higher altitudes, where oxygen levels are lower, the body adapts by increasing the breathing rate to compensate for the reduced oxygen availability.

Conclusion: Gases We Breathe In and Breathe Out

The exchange of gases during the process of breathing is a remarkable and intricate mechanism that sustains life. From the inhalation of oxygen to its utilization in cellular respiration and the subsequent exhalation of carbon dioxide, the respiratory system plays a vital role in maintaining the body’s balance.

Understanding the dynamics of breathing not only sheds light on the physiological processes within our bodies but also emphasizes the delicate interplay between environmental factors and respiratory health. As we continue to explore the complexities of respiratory physiology, we gain insights that contribute to advancements in medical science and the development of effective treatments for respiratory disorders.

FAQs: Gases: We Breathe In and Breathe Out

Are There any Other Gases we can Breathe?

Apart from oxygen and carbon dioxide, we breathe many other gases like nitrogen, water vapor, argon, krypton, etc. This happens because our nose cannot filter only oxygen from the atmospheric air inhaled.

What gas is Breathed in and Out?

Nitrogen and oxygen is breathed in from the atmosphere. Carbon dioxide is breathed out.

What is the Difference Between Breathing in and Breathing Out?

The air we breathe in contains oxygen and other gases. Breathing in is called inhalation and breathing out is called exhalation that releases carbon dioxide.

What are the Gases in Inhaled and Exhaled Air?

Inhaled air includes around 21%oxygen, 0.04% carbon dioxide and 78%nitrogen whereas exhaled air has approximately 16% oxygen, 4% carbon dioxide and likewise 78% nitrogen.

Do we breathe in nitrogen?

We inhale nitrogen the most. But oxygen is the gas that is taken up by the body in maximum volume.