Alveoli

Definition

Alveoli are the tiny air sacs located at the ends of the respiratory bronchioles in the lungs. They are the functional units of the respiratory system, responsible for the exchange of oxygen and carbon dioxide between the air and the bloodstream during the process of respiration.

5 Must Know Facts For Your Next Test

1. Alveoli have a very thin, permeable wall that allows for efficient gas exchange between the air and the bloodstream.
2. The large surface area of the alveoli, combined with their thin walls, facilitates the rapid diffusion of oxygen and carbon dioxide.
3. Alveolar macrophages, specialized immune cells, patrol the alveoli and help protect the lungs from infection and other threats.
4. Surfactant production by type II alveolar cells is crucial for maintaining the structural integrity of the alveoli and preventing their collapse.
5. Damage or impairment of the alveoli can lead to respiratory diseases such as emphysema, pulmonary edema, and acute respiratory distress syndrome (ARDS).

Review Questions

• Explain the role of alveoli in the process of oxygenation and gas exchange.
  • Alveoli are the primary site of gas exchange in the respiratory system. The thin, permeable walls of the alveoli allow for the efficient diffusion of oxygen from the air in the alveoli into the bloodstream, and the diffusion of carbon dioxide from the bloodstream into the alveoli for exhalation. This exchange of gases is the core function of the alveoli, ensuring that the body receives the necessary oxygen and removes the waste product, carbon dioxide, to maintain proper respiratory and metabolic processes.
• Describe how the structure of alveoli is adapted to facilitate gas exchange.
  • The alveoli have a large surface area, with an estimated 300 to 500 million alveoli in the human lungs. This expansive surface area, combined with the thin, permeable walls of the alveoli, allows for rapid diffusion of gases between the air and the bloodstream. Additionally, the alveoli are surrounded by a dense network of capillaries, which brings the blood in close proximity to the air in the alveoli, further enhancing the efficiency of gas exchange. The production of surfactant by type II alveolar cells also plays a crucial role in maintaining the structural integrity of the alveoli and preventing their collapse during exhalation.
• Analyze the potential consequences of alveolar damage or impairment, and how this might impact respiratory function and overall health.
  • Damage or impairment of the alveoli can have serious consequences for respiratory function and overall health. For example, in emphysema, the alveolar walls are damaged and lose their elasticity, leading to the enlargement of the alveoli and a decrease in the surface area available for gas exchange. This can result in reduced oxygen absorption and impaired carbon dioxide removal, causing respiratory distress and other complications. Similarly, in pulmonary edema, fluid buildup in the alveoli can interfere with gas exchange, while in acute respiratory distress syndrome (ARDS), the alveoli can become inflamed and damaged, leading to respiratory failure. Maintaining the structural integrity and functional capacity of the alveoli is crucial for ensuring proper respiratory and metabolic processes throughout the body.

Related terms

Pulmonary Alveoli: The tiny air sacs in the lungs where gas exchange occurs between the air and the blood.

Alveolar Ducts: The short tubes that connect the respiratory bronchioles to the alveolar sacs, facilitating the movement of air into and out of the alveoli.

Surfactant:

A substance produced by type II alveolar cells that reduces the surface tension within the alveoli, preventing their collapse during exhalation.