NURS 311: Gas Exchange at alveolus level

Gaseous Exchange Overview

• Gaseous exchange refers to the process of oxygen (O2) and carbon dioxide (CO2) movement between the lungs and blood.

Pathway of Air into the Lungs

• Air passes into the lungs via:

  • Bronchi: The main passageways that direct air into the lungs.

  • Bronchioles: Smaller branches of the bronchi that lead to the alveoli.

  • Alveoli: Tiny air sacs where gaseous exchange occurs.

Structure and Function of Alveoli

• Alveoli are individual hollow cavities contained within alveolar sacs.

• There are approximately 3 million alveoli in an average adult lung.

• Alveoli have:

  • Very thin walls that facilitate the exchange of oxygen and carbon dioxide.

  • A surrounding network of capillaries, which are small blood vessels.

Mechanism of Gaseous Exchange

• Gaseous exchange occurs through the process of diffusion:

  • Diffusion: The movement of molecules from an area of high concentration to an area of low concentration.

  • In the context of gaseous exchange:

  • The blood in capillaries surrounding the alveoli has a lower concentration of oxygen compared to the air present in the alveoli.

    • Thus, oxygen diffuses from the alveoli into the capillaries.

  • Conversely, the blood in the capillaries has a higher concentration of CO2 compared to the air in the alveoli.

    • Therefore, CO2 diffuses from the capillaries into the alveoli.

Factors Affecting Diffusion

• Both the alveoli and capillaries possess walls that are only one cell thick.

• This minimal thickness allows for efficient gas diffusion between the two structures.

Exhalation of Carbon Dioxide

• Once CO2 has diffused into the alveoli, it can then be exhaled or breathed out.

Observing Gaseous Exchange

• The results of the gaseous exchange can be observed by comparing the composition of the air we breathe in with the air we breathe out.

Additional Resources

• For more information or interactive quizzes related to this topic, visit teachpe.com.