Alveoli

Definition

Alveoli are tiny, balloon-like structures in the lungs where gas exchange occurs. They are essential for respiration, as they provide a large surface area for oxygen to enter the blood and carbon dioxide to be expelled. The design of alveoli, with their thin walls and extensive capillary network, makes them highly efficient in facilitating this gas exchange process.

5 Must Know Facts For Your Next Test

1. Alveoli are surrounded by a dense network of capillaries, allowing for efficient gas exchange between the air and blood.
2. There are approximately 300 million alveoli in an adult human lung, providing a surface area roughly the size of a tennis court.
3. The walls of alveoli are made up of a single layer of epithelial cells, which facilitates rapid diffusion of gases.
4. Alveolar macrophages are immune cells present in the alveoli that help protect against pathogens and debris inhaled into the lungs.
5. In conditions like emphysema, the structure and function of alveoli can be compromised, leading to reduced gas exchange efficiency.

Review Questions

• How do the structural features of alveoli facilitate gas exchange in the lungs?
  • The structure of alveoli is specifically designed to maximize gas exchange efficiency. Their thin walls consist of a single layer of epithelial cells, which reduces the distance oxygen and carbon dioxide must diffuse. Additionally, the large surface area created by millions of alveoli allows for a greater volume of gases to be exchanged simultaneously. The proximity of alveoli to capillaries further enhances this process, ensuring that oxygen enters the bloodstream and carbon dioxide is removed effectively.
• Discuss the role of surfactant in maintaining alveolar function and how its deficiency can impact respiratory health.
  • Surfactant plays a vital role in maintaining proper alveolar function by reducing surface tension within the alveoli. This prevents the alveoli from collapsing during exhalation, ensuring they remain open and ready for gas exchange. A deficiency in surfactant can lead to conditions such as respiratory distress syndrome in infants, where collapsed alveoli hinder breathing and gas exchange. This illustrates how crucial surfactant is for normal respiratory function and overall lung health.
• Evaluate the consequences of compromised alveolar function due to diseases such as emphysema on overall respiratory efficiency.
  • Compromised alveolar function due to diseases like emphysema significantly impacts respiratory efficiency. In emphysema, the destruction of alveolar walls reduces their surface area and elasticity, making it difficult for patients to breathe and effectively exchange gases. As a result, individuals experience symptoms such as shortness of breath and decreased oxygen intake. This decline not only affects physical activity levels but can also lead to further health complications due to inadequate oxygenation throughout the body.

Related terms

Bronchioles: The smaller branches of the bronchi that lead to the alveoli, playing a crucial role in directing air into the lungs.

Surfactant: A substance produced by the alveoli that reduces surface tension, preventing the collapse of these structures during exhalation.

Respiration: The process by which oxygen is taken in and carbon dioxide is expelled, involving both inhalation and exhalation.