How is the sum of anatomical dead space and pathological alveolar dead space referred to?

The term used to describe the sum of anatomical dead space and pathological alveolar dead space is physiological dead space. Anatomical dead space refers to parts of the respiratory system where gas exchange does not occur, such as the trachea and bronchi. Pathological alveolar dead space occurs when some alveoli are ventilated but not perfused, meaning that even though air is present in these alveoli, gas exchange does not take place effectively because blood flow is inadequate or absent.

By combining these two components, physiological dead space accounts for all areas of the lungs that do not contribute to effective gas exchange. This is particularly important in clinical settings, as it provides insight into lung function and the efficiency of breathing. Understanding this concept is crucial for assessing respiratory conditions and managing patients with lung diseases.

The other options refer to different lung volumes or capacities and do not encompass the combination of both anatomical and pathological dead spaces.