Question

lo 4.2. what is the function of the capillaries surrounding the alveoli?
protect the alveoli from infection
transport nutrients to the alveoli
regulate blood pressure in the lungs
increase surface area for gas exchange
facilitate gas exchange

Explanation:

The alveoli are tiny air - sacs in the lungs where gas exchange occurs. Capillaries surrounding the alveoli are extremely thin - walled blood vessels. Oxygen from the alveoli diffuses into the capillaries (to be transported to the body's cells), and carbon dioxide from the capillaries diffuses into the alveoli (to be exhaled). This process is gas exchange.

• Protecting the alveoli from infection is more of an immune - related function (e.g., macrophages in the lungs).
• Transporting nutrients to the alveoli is not the main role of these capillaries; their main role is gas exchange.
• Regulating blood pressure in the lungs is a function of larger blood vessels and the overall cardiovascular system's regulatory mechanisms, not the specific role of alveolar - surrounding capillaries.
• Increasing surface area for gas exchange is more related to the structure of the alveoli themselves (many small alveoli increase surface area), while the capillaries' main role is facilitating the actual gas exchange process (diffusion of gases between alveoli and blood).

Answer:

Facilitate gas exchange