The Tracheo-bronchial Tree: the Gita’s “Root-Up Branches-Down” Tree

 

ūrdhvamūlamadhaḥśākhamakṣvatthaṃ prāhuravyayam |

chandāṃsi yasya parṇāni yastaṃ veda sa vedavit || 15.1 ||

adhakṣcordhvaṃ prasṛtāstasya śākhā guṇapravṛddhā viṣayapravālāḥ |

adhakṣca mūlānyanusantatāni karmānubandhīni manuṣyaloke || 15.2 ||

 

In the fifteenth chapter of the Bhagavad Gita, Krsna, with a view to imbue Arjuna with the feeling of dispassion (vairajna), introduces the metaphor (rupaka) of “samsara vrksa,” the tree of material existence. The tree that Krsna speaks of is an inverted one; it is a Asvattha (ficus religiosa) whose root (mula) is above (urdhva) and whose branches (sakham) are below (adhah). This “inverted tree” is supposed to represent samsara, with its transitory yet uninterrupted-flow-like (pravaha) nature. The (sub) branches of this “inverted tree” extend both up and down.

This “inverted tree” is the tracheo-bronchial tree of the lungs.

In order to fully appreciate this great metaphor, found also in the Katha Upanisad and the Mahabharata, one must keep in mind that Krsna is the immanent lord (paramatma), speaking to Arjuna within the microcosm. Further, “material existence,” in the context of the Upanisads, has more to do with the body—the respiratory process in particular—than with the (external) world of the sense-objects.

The “root”of this (respiratory) “tree” is the trachea while its “branches” are the various bronchi which go on branching dichotomously. The “leaves” of this “tree” are said to be the metres of the Vedas. There is a greater likelihood of these being the respiratory bronchioles as these exist at the terminal end of the tracheo-bronchial tree; but they may also stand simply for the bronchioles.

The acinus is like the zone of the leaves because it is here that "food" production takes place; it's here that the carbon dioxide is absorbed and oxygen is released. The acinus marks a different functional component in the r. tree, like the leaves which are functionally different from the branches

According to Govinda Misra, the inverted tree is situated in the form of a body; obviously he is referring to the virat purusa ("deha rupe sthita").

The different regions of the bronchial tree are compared to the different parts of a tree. So there's the trunk, the larger branches (these two, the central axial region, must constitute the central region of jambudvipa), the smaller branches, the leaves, the shoots and the fruits and the flowers. The branch region probably ends with the "twigs," the terminal bronchioles.