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

How is waste carbon dioxide expelled from the body?

1. Through absorption

2. Through digestion

3. Through expiration

4. Through circulation

The correct answer is: Through expiration

The correct answer is connected to the physiological process of breathing, specifically the role of the respiratory system in gas exchange. The body produces carbon dioxide as a byproduct of cellular metabolism, and it must be expelled to maintain acid-base balance and overall homeostasis. During the process of expiration, the diaphragm and other respiratory muscles contract to decrease the volume of the thoracic cavity, leading to an increase in pressure that forces air out of the lungs. This air, which contains a higher concentration of carbon dioxide than the surrounding atmosphere, is expelled from the body. This process is vital for removing excess carbon dioxide, which, if accumulated, can lead to respiratory acidosis and other health issues. Absorption refers to the process by which substances are taken up into the body, typically through the digestive system or skin, and is not involved in carbon dioxide expulsion. Digestion involves breaking down food and nutrients in the gastrointestinal tract, not the removal of waste gases. Circulation plays a role in transporting carbon dioxide from the tissues to the lungs via the bloodstream, but it is the respiratory process of expiration that ultimately eliminates carbon dioxide from the body.