Gas exchange in a body
What is observed in the image is the process of gas exchange that occurs within a body. At the top of the image, in red color, can be seen a set of alveoli (the structural and functional unit found within the lungs), while below these it can be observed a blood capillary.
The blood capillary defuses the carbon dioxide previously collected from the body to the alveolus, which will then send it out of the body through the process of exhalation. At the same time, the oxygen diffuses from the alveolus to the blood capillary, which will carry it to oxygenate the rest of the body.
This exchange occurs by passive diffusion, that is, in favor of the gas concentration gradient and without energy expenditure.