An alveolus (plural: alveoli) is a tiny air sac found in the lungs of mammals. These sacs are the site of gas exchange between the lungs and the bloodstream. Each alveolus is surrounded by a network of blood vessels called capillaries, which allow oxygen and carbon dioxide to diffuse across the thin walls of the sacs and into or out of the bloodstream.
An alveolus (plural: alveoli) is a tiny air sac found in the lungs of mammals. These sacs are the site of gas exchange between the lungs and the bloodstream. Each alveolus is surrounded by a network of blood vessels called capillaries, which allow oxygen and carbon dioxide to diffuse across the thin walls of the sacs and into or out of the bloodstream.
The structure and function of alveoli play a crucial role in the respiratory system, facilitating the exchange of oxygen and carbon dioxide necessary for sustaining life. The collective surface area of all the alveoli in the human lungs is vast, providing an extensive surface for efficient gas exchange. This large surface area allows for a rapid exchange of oxygen and carbon dioxide, optimizing respiratory efficiency.
Alveoli are lined with a thin layer of surfactant, a substance that reduces surface tension. This surfactant helps prevent the collapse of the alveoli during exhalation and ensures that the alveoli remain open for efficient gas exchange. Surfactant production is crucial, particularly for the proper functioning of the lungs in premature infants.
Alveoli are surrounded by elastic fibers, allowing them to expand and contract during inhalation and exhalation. This elasticity helps maintain the integrity of the alveoli and facilitates the movement of gases in and out of the lungs.
Alveoli are patrolled by immune cells, primarily macrophages, that play a vital role in defense against pathogens and foreign particles. These cells help to keep the air sacs clear of debris and protect the respiratory system from infections.
The thin walls of the alveoli, along with the adjacent capillaries, form what is known as the respiratory membrane. This membrane is incredibly thin to facilitate the efficient diffusion of gases. Oxygen passes from the air sacs into the bloodstream, while carbon dioxide moves from the bloodstream into the alveoli for eventual exhalation.
Once oxygen diffuses into the bloodstream, it binds to hemoglobin in red blood cells and is transported to various tissues and organs throughout the body. Simultaneously, carbon dioxide produced by cellular metabolism diffuses into the bloodstream and is transported back to the lungs for elimination during exhalation.
Understanding the intricate structure and functions of alveoli provides insight into the complexity and efficiency of the respiratory system. The delicate balance maintained within these tiny air sacs is essential for sustaining life and ensuring the optimal exchange of gases required for cellular function.