Alveoli

Definition

Tiny air sacs located at the end of bronchioles in the lungs where gas exchange occurs. Alveoli are crucial for oxygen entering the bloodstream and carbon dioxide being expelled from it.

5 Must Know Facts For Your Next Test

1. Alveoli increase the surface area of the lungs to allow for efficient gas exchange.
2. There are approximately 300 million alveoli in a healthy human lung.
3. Alveoli are surrounded by a network of capillaries where gas exchange takes place.
4. The walls of alveoli are extremely thin to facilitate rapid diffusion of gases.
5. Surfactant, a substance produced by cells within alveoli, reduces surface tension and prevents collapse.

Review Questions

• What is the primary function of alveoli in the respiratory system?
• How do alveoli facilitate gas exchange between the air and blood?
• Why is surfactant important for alveolar function?

Related terms

Bronchioles:

Small airways in the lungs that lead from the bronchi to the alveoli.

Capillaries: Tiny blood vessels where gas exchange occurs between blood and tissues.

Surfactant: A substance that reduces surface tension within the alveoli, preventing their collapse during exhalation.