Alveoli

Definition

Alveoli are tiny air sacs located in the lungs that are crucial for gas exchange in mammals. They provide a large surface area for oxygen to diffuse into the blood and for carbon dioxide to diffuse out, making them essential components of the respiratory system.

5 Must Know Facts For Your Next Test

1. Alveoli increase the surface area of the lungs to approximately 70 square meters, allowing for efficient gas exchange.
2. Each alveolus is surrounded by a network of capillaries, where oxygen and carbon dioxide are exchanged via diffusion.
3. The walls of the alveoli are extremely thin (one cell thick) which facilitates the rapid diffusion of gases.
4. Surfactant, produced by type II alveolar cells, plays a critical role in reducing surface tension and preventing the collapse of alveoli during exhalation.
5. Damage to the alveoli can lead to respiratory diseases like emphysema, which decreases their function and surface area.

Review Questions

• How do alveoli facilitate efficient gas exchange in mammals?
  • Alveoli facilitate efficient gas exchange due to their large surface area and thin walls, which allow oxygen to diffuse into the bloodstream while carbon dioxide diffuses out. The presence of a dense network of capillaries surrounding each alveolus further enhances this process, ensuring that gases can be exchanged quickly and effectively. Additionally, surfactant helps maintain the structure of the alveoli, allowing them to remain open during respiration.
• Discuss the role of surfactant in maintaining proper lung function related to alveoli.
  • Surfactant is crucial for maintaining proper lung function because it reduces surface tension within the alveoli. This reduction in surface tension prevents the alveoli from collapsing during exhalation and ensures that they remain open for gas exchange during inhalation. Without sufficient surfactant, as seen in conditions like neonatal respiratory distress syndrome, alveoli can collapse, leading to significant difficulties in breathing and gas exchange.
• Evaluate how damage to alveoli impacts overall respiratory efficiency and what implications this has for human health.
  • Damage to alveoli, such as that caused by smoking or diseases like emphysema, severely impacts respiratory efficiency by reducing the surface area available for gas exchange. This results in lower oxygen levels in the blood and higher levels of carbon dioxide, which can lead to symptoms such as shortness of breath and fatigue. The long-term implications for human health include chronic respiratory problems, decreased quality of life, and increased risk of cardiovascular issues due to insufficient oxygen supply.

Related terms

bronchioles: The small air passages that branch off from the bronchi and lead to the alveoli, playing a key role in directing air into the lung's gas exchange areas.

surfactant: A substance produced in the lungs that reduces surface tension in the alveoli, preventing their collapse and making breathing easier.

capillaries: The smallest blood vessels surrounding the alveoli where gas exchange occurs between air in the alveoli and blood in the capillaries.