Which of the following is NOT one of the pressures within the respiratory system?

Respiratory pressures are essential for understanding how the lungs function during breathing. Alveolar pressure refers to the pressure within the alveoli, which plays a crucial role in the mechanics of inhalation and exhalation. Pleural pressure is the pressure in the pleural cavity, which helps keep the lungs inflated and assists in the breathing process. Abdominal pressure pertains to the pressure within the abdominal cavity, which can influence lung function, especially during heavy breathing or forced exhalation.

Airway pressure, while an important concept in the dynamics of airflow through the airways, is not typically categorized as one of the fundamental pressures in the respiratory system. Instead, it corresponds more to the pressure changes that occur due to airflow and resistance in the bronchial tree during breathing. Thus, it does not belong in the primary categorization alongside alveolar, pleural, and abdominal pressures, making it the correct choice for the question.