BioMedical Admissions Test (BMAT) 2026 – 400 Free Practice Questions to Pass the Exam

The alveoli are tiny air sacs located at the end of the respiratory tree and are the primary site of gas exchange in the lungs. Their structure is crucial for this function; they have extremely thin walls and a large surface area that allows for efficient diffusion of oxygen and carbon dioxide.

Oxygen from the air inside the alveoli diffuses into the blood within nearby capillaries, while carbon dioxide in the blood moves in the opposite direction to be exhaled. This process is essential for maintaining proper oxygen levels in the body and eliminating carbon dioxide, a waste product of metabolism.

In contrast, the bronchioles, trachea, and pulmonary artery play different roles. The bronchioles are smaller air passages that lead to the alveoli but do not participate in gas exchange themselves. The trachea is the windpipe that transports air to the bronchi and does not directly handle gas exchange. The pulmonary artery carries deoxygenated blood from the heart to the lungs but does not itself play a role in the exchange of gases.