Internal Respiration and Prana
Physiologists know that internal respiration is not a globally structured phenomenon but a multitude of operations that can be analyzed in many different ways. These operations take in oxygen and release carbon dioxide. They participate in the process through which these two molecules are distributed in the organism These mechanisms are consumers of energy more than organismic regulators. They do not consume oxygen to produce carbon dioxide. They are content to carry out their mission utilizing their environment as a source of supply and as a means of waste disposal. Some global physiological mechanisms, like venous circulation, then gather the excess amount of carbon dioxide to expel it from the organism, notably through external respiration (exhalation) but also by other avenues like perspiration.
This introduction to internal respiration is also an introduction to the notion of prana. I do not know what the Hindus knew relative to internal respiration,32 but the yogis had observed, clinically at least, that respiration intimately influenced all of the physiological mechanisms of the organism Prana is this dynamic interaction between respiration and the physiological mechanisms. Their theories were based on whatever knowledge and philosophical speculations were fashionable at a given moment. This explains why they sometimes appear folkloric and magical to some physiologists. What is astonishing with regard to the theories about prana is the extent to which the intuition of the yogis is fundamentally correct, in the measure in which they perceived how breathing had a profound impact on the dynamics of the organisms, moods, and thoughts. The yogis developed, in the course of the centuries, an impressive number of explicit techniques, capable of having foreseeable effect on this nebulous group of mechanisms that they called prana.