Which of the following organs is NOT a part of the respiratory system?

• A. Airway
• B. Lungs
• C. Heart
• D. Rib cage

Answer: (C)

The heart is not a part of the respiratory system. The primary function of the respiratory system is to facilitate the exchange of gases, specifically oxygen and carbon dioxide, which occurs primarily in the lungs and through the airway. The lungs serve as the main organs where this gas exchange takes place, while the airway includes various structures such as the trachea and bronchi that transport air in and out of the lungs.

The rib cage, although not an organ like the lungs or airway, plays a crucial role in the respiratory process by protecting the lungs and assisting with the mechanics of breathing. It allows for the expansion and contraction of the chest cavity, facilitating inhalation and exhalation.

In contrast, while the heart is essential for overall bodily function by pumping blood and supplying oxygen to tissues, it is part of the circulatory system rather than the respiratory system. This distinction confirms that the heart does not directly participate in the processes involved in respiration.