Which specialized tissue sacs transfer oxygen and carbon dioxide during respiration?

Alveoli are the small, specialized tissue sacs within the lungs that play a crucial role in the respiratory process. These tiny air sacs are the primary site for the exchange of gases—specifically oxygen and carbon dioxide—between the air and the bloodstream. Alveoli are surrounded by a network of capillaries, allowing oxygen from inhaled air to diffuse into the blood while carbon dioxide from the blood is released into the alveoli to be exhaled.

The structure of the alveoli, being thin-walled and highly vascularized, maximizes surface area for gas exchange, enabling efficient oxygen uptake and carbon dioxide removal. This is essential for maintaining the body’s respiratory function. In contrast, bronchioles are part of the airways that lead to the alveoli but are not directly involved in gas exchange. Canaliculi refer to small channels in bone tissue and do not relate to respiration, while erythrocytes, or red blood cells, transport oxygen and carbon dioxide within the bloodstream but do not themselves facilitate gas exchange in the lungs. Thus, alveoli are specifically designed for this critical function in the respiratory system.