THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -Tiny air sacs at the end of the bronchioles (tiny branches of air tubes in the lungs). The alveoli are where the lungs and the blood exchange oxygen and carbon dioxide during the process of breathing in and breathing out.

Detailed explanation-2: -In your lungs, the main airways, called bronchi, branch off into smaller and smaller passageways. The smallest airways, called bronchioles, lead to tiny air sacs called alveoli.

Detailed explanation-3: -Each lung contains millions of these sacs. The small round alveoli allow for an amazingly large surface area for this gas exchange to take place. Remember, the blood capillaries must be in contact with the respiratory surface for gas exchange to take place.