Respiratory pathway is conventionally understood as catabolic pathway because it involves breaking down the respiratory substrates. For example; carbohydrates, fats and proteins are broken down to produce energy. But whenever the organism needs to make fatty acid or protein; it needs some intermediate products of respiration. For example; Acetyl CoA would be withdrawn from the respiratory pathway if there is a need to manufacture fatty acid or protein. It is seen that respiratory pathway is involved in both catabolic and anabolic processes. Hence, respiratory pathway is referred to as an amphibollc pathway.