What is included in the respiratory system?

The respiratory system is primarily responsible for the process of breathing and the exchange of gases, particularly oxygen and carbon dioxide, in the body. It includes structures that facilitate the movement of air into and out of the lungs. The nose and mouth are important entry points for air, while the trachea serves as a passageway that directs air into the bronchi and subsequently into the lungs. These components play a critical role in ensuring that air can be inhaled and exhaled effectively.

In contrast, the other options contain organs that are part of different systems. For example, the heart, lungs, and blood vessels are components of the circulatory system, which works closely with the respiratory system but is not exclusively part of it. Similarly, the stomach and intestines are involved in digestion, making them part of the digestive system, while the kidneys and urinary bladder pertain to the urinary system, which is responsible for filtering waste and regulating water balance in the body. Thus, fundamentally, the respiratory system is characterized by its specific structures that enable gas exchange, and the correct answer reflects that focus.