Answer: The epithelial cells
The endothelial cells .
The epithelial cells are pulmonary while the endothelial are vascular
These cells exist as tight-two celled structure for gas exchange in the lungs
They are moistened , thin layered , and use diffuse gradient of oxygen and carbon dioxide to move gases across their wall.s
They are well lined with blood capillaries for rapid absorption of gases into the blood stream,
