Answer:
alveoli
Step-by-step explanation:
The alveoli are small pockets present in the lungs. They are extremely important in the living organism, because the carbon dioxide that is excreted passes directly from the blood to the alveoli. These pulmonary pockets are located inside the lungs and originate through the bronchial branches, have a spongy appearance and vascularized walls.
It is in the alveoli that the gas exchange essential for living organisms occurs. The alveoli have a very thin membrane that separates air from blood, it is because of this membrane that carbon dioxide is excreted.