Alveoli

Definition

Alveoli are tiny, balloon-like structures located in the lungs where gas exchange occurs between the air and the bloodstream. They play a crucial role in respiratory function, allowing oxygen to enter the blood and carbon dioxide to be expelled. The extensive surface area provided by alveoli enhances the efficiency of gas exchange, making them vital components of the respiratory system.

5 Must Know Facts For Your Next Test

1. Each lung contains approximately 300 million alveoli, providing a vast surface area for gas exchange.
2. The walls of alveoli are only one cell thick, allowing for efficient diffusion of oxygen and carbon dioxide between the air and blood.
3. Alveoli are surrounded by a network of capillaries, ensuring that oxygen enters the bloodstream quickly while carbon dioxide is removed.
4. Damage to alveoli can lead to conditions such as emphysema, where the surface area for gas exchange is reduced, impairing respiratory function.
5. The presence of surfactant in alveoli is crucial as it prevents their collapse during exhalation and maintains lung stability.

Review Questions

• How do the structural features of alveoli enhance their function in gas exchange?
  • Alveoli have several structural features that enhance their function in gas exchange. Their thin walls allow for quick diffusion of gases, while their large surface area increases the amount of air that can be exchanged at any given time. The extensive network of capillaries surrounding each alveolus ensures that oxygen can easily enter the bloodstream while carbon dioxide is expelled efficiently. Together, these features make alveoli highly effective at facilitating respiration.
• Discuss the role of surfactant in maintaining alveolar function and its impact on respiratory health.
  • Surfactant plays a vital role in maintaining alveolar function by reducing surface tension within the alveoli. This reduction in surface tension prevents alveoli from collapsing during exhalation and ensures that they remain open for effective gas exchange during inhalation. In conditions where surfactant production is impaired, such as neonatal respiratory distress syndrome or acute respiratory distress syndrome (ARDS), alveoli can collapse, leading to decreased lung compliance and impaired oxygenation, highlighting the importance of surfactant in respiratory health.
• Evaluate how diseases affecting the alveoli impact overall respiratory efficiency and oxygen transport in the body.
  • Diseases that affect the alveoli, such as chronic obstructive pulmonary disease (COPD) or pneumonia, significantly impact overall respiratory efficiency and oxygen transport. In these conditions, the structure and function of alveoli are compromised, leading to reduced surface area for gas exchange and impaired diffusion of gases. As a result, less oxygen enters the bloodstream, causing systemic hypoxia and increased carbon dioxide levels. This impairment not only affects individual organ systems but can also lead to widespread physiological consequences, including fatigue, decreased exercise capacity, and complications in other organs due to inadequate oxygen supply.

Related terms

Bronchioles: Small air passages that branch off from the bronchi and lead to the alveoli, facilitating airflow within the lungs.

Surfactant:

A substance produced by alveolar cells that reduces surface tension within the alveoli, preventing their collapse and aiding in gas exchange.

Diffusion:

The process by which molecules move from an area of higher concentration to an area of lower concentration, essential for gas exchange in the alveoli.