Sri Aurobindo translates Prashna Upanishad, Third Question, Verses 4-5: “As an Emperor commandeth his officers, and he sayeth to one, ‘Govern for me these villages,’ and to another, “Govern for me these others,’ so this breath, the Life, appointeth the other breaths each in his province. In the anus and the organ of pleasure is the lower breath, and in the eyes and the ears, the mouth and the nose, the main breath itself is seated: but the medial breath is in the middle. This is he that equally distributeth the burnt offering of food: for from this are the seven fires born.”
The universal Life-Force, when it operates in the individual human being, has created subsidiary movements of energy, of which there are five primary and innumerable secondary motions. The five primary are called prana, apana, samana, udana and vyana. Briefly, Prana, at the individual level, is considered the main breath, operative in the upper regions that govern respiration and other primary sensory functions. Apana is the lower breath, operating various forms of elimination functions. Samana operates through the central part of the being, distributing the pranic force through the body and its internal organs, which provides digestion and nourishment to the physical body and its actions. The seven fires referenced in these verses represent the sense organs, 2 eyes, 2 ears, 2 nostrils and the mouth, governing sight, hearing, smell and taste, according to traditional commentators.
Sri Aurobindo, The Upanishads, Prashna Upanishad, pp.297-315