Alveoli

Definition

Alveoli are tiny air sacs located at the end of the bronchioles in the lungs, essential for gas exchange during respiration. They are surrounded by capillaries, allowing oxygen to enter the bloodstream and carbon dioxide to be expelled. Their structure provides a large surface area for effective gas exchange, making them crucial in the respiratory system's function.

5 Must Know Facts For Your Next Test

1. Alveoli are approximately 300 million in number in a healthy adult lung, significantly increasing the surface area for gas exchange.
2. The walls of the alveoli are extremely thin (one cell thick), which helps facilitate rapid diffusion of gases.
3. Each alveolus is surrounded by a network of capillaries where blood is oxygenated and carbon dioxide is removed.
4. Damage to alveoli, such as from smoking or diseases like emphysema, can severely impact respiratory efficiency and overall health.
5. The process of gas exchange in the alveoli is driven by differences in partial pressure of gases, following Fick's law of diffusion.

Review Questions

• How do alveoli contribute to efficient gas exchange in the lungs?
  • Alveoli are crucial for efficient gas exchange due to their large surface area and thin walls. The vast number of alveoli in the lungs increases the area available for oxygen to diffuse into the blood while allowing carbon dioxide to diffuse out. The close proximity of alveoli to capillaries enables rapid gas exchange driven by concentration gradients, ensuring that oxygen enters the bloodstream efficiently.
• Discuss the role of surfactant in alveolar function and its importance in respiratory health.
  • Surfactant plays a vital role in maintaining alveolar stability by reducing surface tension within the alveoli. This prevents alveolar collapse during exhalation, ensuring that they remain open for gas exchange. Without adequate surfactant, as seen in conditions like Neonatal Respiratory Distress Syndrome, infants can struggle with breathing, highlighting its importance in respiratory health and functionality.
• Evaluate how damage to alveoli impacts overall respiratory function and oxygen delivery in the body.
  • Damage to alveoli significantly hampers respiratory function by reducing the surface area available for gas exchange, leading to conditions such as chronic obstructive pulmonary disease (COPD) or emphysema. This results in decreased oxygen delivery to the bloodstream and inefficient removal of carbon dioxide, causing symptoms like shortness of breath and reduced exercise capacity. The systemic effects can include fatigue and decreased physical performance due to insufficient oxygen supply during activities.

Related terms

Bronchioles:

The smaller branches of the bronchial tubes that lead from the trachea to the alveoli, playing a key role in conducting air to the lungs.

Surfactant: A substance produced in the alveoli that reduces surface tension, preventing the alveoli from collapsing and aiding in lung function.

Respiration: The process of exchanging gases between the body and the environment, which involves inhaling oxygen and exhaling carbon dioxide, facilitated by the alveoli.