Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

What are alveoli?

1. Air passages in the trachea

2. Air sacs in the lungs

3. Cells that transport oxygen

4. Tissues that protect the lungs

The correct answer is: Air sacs in the lungs

Alveoli are small, balloon-like structures within the lungs where the exchange of oxygen and carbon dioxide takes place. They are essential for respiration, allowing oxygen to enter the bloodstream and carbon dioxide to be expelled from the body. The walls of the alveoli are extremely thin and lined with a moist surface, making them ideal for the diffusion of gases. This function is critical in maintaining the body's gas exchange process, supporting the overall respiratory system and ensuring that oxygen is available for cellular functions throughout the body. The other choices do not accurately describe alveoli. The air passages in the trachea refer to the larger airways that transport air to the lungs, while cells that transport oxygen, such as red blood cells, are involved in carrying oxygen but are not structurally related to the alveoli. Lastly, although lung tissues as a whole protect and support the respiratory system, they do not fulfill the specific role of the alveoli in gas exchange. Thus, the correct answer highlights the primary function and structure of alveoli in the respiratory process.