Alveolar cells, also known as type I alveolar cells and type II alveolar cells, are specialized cells found in the lungs. They play a crucial role in the respiratory system by forming the walls of the alveoli, which are tiny air sacs where gas exchange occurs. Type I cells are thin and facilitate the diffusion of oxygen and carbon dioxide, while type II cells produce a substance called surfactant that reduces surface tension, preventing the alveoli from collapsing. These cells are essential for maintaining healthy lung function. The surfactant produced by type II alveolar cells also helps keep the alveoli stable during breathing. When we inhale, oxygen enters the alveoli, and carbon dioxide is expelled, allowing our bodies to function properly. Any damage to these cells can lead to respiratory issues, highlighting their importance in overall health.