Which term describes the process of air entering the lungs?

Which term describes the process of air entering the lungs?

• A. Expiration
• B. Respiration
• C. Inspiration
• D. Diffusion

Answer: (C)

Air entering the lungs is called inspiration. It happens when the diaphragm and intercostal muscles contract, expanding the chest and increasing the volume of the thoracic cavity. This creates a slight drop in pressure inside the lungs, causing outside air to flow in through the airways. Expiration is the reverse process, when air exits as the chest cavity relaxes. Diffusion describes the movement of individual gas molecules across membranes (like oxygen moving into the blood at the alveoli), not the act of taking air in. Respiratory terms can refer to breathing in general or cellular processes, but the specific term for drawing air into the lungs is inspiration.

Air entering the lungs is called inspiration. It happens when the diaphragm and intercostal muscles contract, expanding the chest and increasing the volume of the thoracic cavity. This creates a slight drop in pressure inside the lungs, causing outside air to flow in through the airways. Expiration is the reverse process, when air exits as the chest cavity relaxes. Diffusion describes the movement of individual gas molecules across membranes (like oxygen moving into the blood at the alveoli), not the act of taking air in. Respiratory terms can refer to breathing in general or cellular processes, but the specific term for drawing air into the lungs is inspiration.