Alveoli

Definition

Alveoli are tiny air sacs located in the lungs where the exchange of oxygen and carbon dioxide takes place. These structures are essential for respiration, providing a large surface area that allows for efficient gas exchange between the air and blood, playing a critical role in the body's overall respiratory function.

5 Must Know Facts For Your Next Test

1. Alveoli increase the surface area of the lungs, providing approximately 70 square meters for gas exchange, which is essential for meeting the body's oxygen needs.
2. Each alveolus is surrounded by a network of capillaries that facilitate the rapid exchange of gases with the bloodstream.
3. The walls of alveoli are extremely thin (one cell thick), allowing for efficient diffusion of gases between the air in the alveoli and the blood in the capillaries.
4. Diseases such as emphysema can damage the alveoli, reducing their number and elasticity, leading to decreased respiratory efficiency and difficulty in breathing.
5. The presence of surfactant in alveoli is crucial; without it, alveoli would collapse due to high surface tension, making breathing difficult.

Review Questions

• How do alveoli contribute to efficient gas exchange in the lungs?
  • Alveoli contribute to efficient gas exchange by providing a large surface area and a thin barrier between the air and blood. The vast number of alveoli creates an extensive network where oxygen can diffuse into the bloodstream while carbon dioxide diffuses out. This design allows for maximum contact between air and blood, ensuring that enough oxygen enters while removing carbon dioxide effectively.
• What role does surfactant play in maintaining alveolar function, and how would its absence affect respiration?
  • Surfactant plays a crucial role in maintaining alveolar function by reducing surface tension within the alveoli. This prevents them from collapsing during exhalation, allowing for easier inflation during inhalation. Without surfactant, alveoli would be prone to collapse, leading to impaired gas exchange and respiratory distress, as seen in conditions like neonatal respiratory distress syndrome.
• Evaluate how diseases affecting alveoli impact overall respiratory health and the body's ability to deliver oxygen efficiently.
  • Diseases affecting alveoli, such as COPD or pulmonary fibrosis, can severely compromise respiratory health by reducing the number and functionality of these vital structures. This leads to decreased surface area for gas exchange, resulting in lower oxygen levels in the blood and reduced removal of carbon dioxide. The body struggles to meet its oxygen demands during physical activity or even at rest, which can cause fatigue and other systemic issues as organs become starved of oxygen.

Related terms

Bronchioles: Small air passages that branch from the bronchi and lead to the alveoli, allowing air to reach the sites of gas exchange.

Surfactant: A substance produced in the alveoli that reduces surface tension, preventing the collapse of these air sacs during exhalation and ensuring they remain open for gas exchange.

Hemoglobin: A protein in red blood cells that binds to oxygen in the alveoli and transports it throughout the body, playing a crucial role in oxygen delivery.