Alveoli

Definition

Alveoli are tiny, balloon-like structures in the lungs where gas exchange occurs, specifically the exchange of oxygen and carbon dioxide between the air and the bloodstream. These small air sacs are crucial for respiration as they provide a large surface area for gas exchange, facilitating the transfer of oxygen into the blood while removing carbon dioxide from it. The health and function of alveoli directly impact overall respiratory efficiency and can be affected by various diseases.

5 Must Know Facts For Your Next Test

1. Alveoli are surrounded by a network of capillaries that facilitates the diffusion of gases; oxygen enters the blood, while carbon dioxide is expelled.
2. There are approximately 300 million alveoli in healthy adult lungs, providing a vast surface area roughly equivalent to that of a tennis court for gas exchange.
3. Diseases like emphysema and pneumonia can damage alveoli, leading to decreased gas exchange efficiency and respiratory distress.
4. Alveoli have thin walls made up of epithelial cells that allow for easy diffusion of gases; this thin barrier is critical for effective gas exchange.
5. The number and health of alveoli can be influenced by factors such as smoking, environmental pollutants, and genetic predispositions.

Review Questions

• How do alveoli contribute to efficient gas exchange in the lungs?
  • Alveoli are essential for efficient gas exchange due to their large surface area and thin walls that facilitate rapid diffusion. Each alveolus is surrounded by pulmonary capillaries where oxygen from inhaled air diffuses into the bloodstream while carbon dioxide moves from the blood into the alveoli to be exhaled. This structure allows for maximum gas exchange with minimal effort during breathing.
• Discuss the impact of diseases like emphysema on alveolar function and overall respiratory health.
  • Emphysema damages the walls of the alveoli, causing them to lose elasticity and merge into larger sacs, which reduces the total surface area available for gas exchange. As a result, individuals with emphysema experience difficulty breathing and reduced oxygen intake. This impairment can lead to chronic respiratory issues and decreased quality of life as their lungs become less effective at oxygenating blood and removing carbon dioxide.
• Evaluate how environmental factors can influence the health of alveoli and implications for public health.
  • Environmental factors such as air pollution, smoking, and occupational hazards can significantly affect alveolar health by causing inflammation, damage, or dysfunction. For instance, long-term exposure to pollutants can lead to chronic obstructive pulmonary disease (COPD) or other respiratory diseases that compromise alveolar function. Addressing these environmental issues is crucial for improving public health outcomes and reducing healthcare costs related to respiratory illnesses.

Related terms

Surfactant: A substance produced in the alveoli that reduces surface tension, preventing the collapse of these structures and aiding in lung expansion during inhalation.

Bronchioles:

The small air passages that branch from the bronchi and lead directly to the alveoli, playing a key role in directing airflow into the lungs.

Pulmonary Capillaries: Tiny blood vessels that surround the alveoli, where the actual exchange of gases occurs between the air in the alveoli and the blood.