The Pulmonary Artery is a Great Sorcerer

 The pulmonary arterial conduits are looked upon by the ancient anatomists as notorious shape-shifters. They are viewed as demons endowed with the power to change form in accordance with the form of the bronchi. The various forms they assume match the rank and the designation of the bronchial conduits. For smaller bronchi smaller forms are assumed and for larger ones larger; the pulmonary arterial conduit moves exactly in sync with the bronchus.

The bronchioles are matched by the pulmonary arterioles and the respiratory bronchioles by the smaller arterioles in the acinar zone. It is as if the pulmonary arterial conduit is some kind of a great sorcerer or magician, having the power to take on any form of the earthly (bronchial) realm that it wishes. It can be viewed as either personally taking on or sending a subordinate member of the network to assume the form of any member of the bronchial realm.

The tremendous representative capacity of poetical language is utilized to the hilt here; and it is almost as if the poet himself has decided to don the sorcerer's mantle in a bid to match the anatomist!

The Sacrifice of Purusa

 The bronchial tree which is referred to as the samsara vrksa may also be conceived as the body of a man as the various parts of a tree are often compared to the the different portions of the human body such as the trunk, the limbs and the crown. The bigger and heavier branches stemming from the trunk that support the superior and the lighter ones are often compared to hands (for their "holding" and supporting role) for instance.  The commentary [] on the Gita also says [] which is picked up by Govinda Misra for incorporating into his verse translation ("deha rupe sthita..."). It is this "deha" (body) that is known in ancient intellectual circles as the "virat purusa," the "great cosmic person" (more appropriately, "respiratory man" as the context is microcosmic) , one of the most pivotal concepts in ancient Indian thought.

There is the primary bronchus playing the role of the main axis of the body of this tree. By virtue of its supporting role it may be compared to the trunk of an actual tree. It is connected to an upper lobe bronchus, the middle (or the lingular) lobe bronchus and the lower lobe bronchus.

Now this may be regarded as the initial state of the virat purusa--the bronchial tree represented metaphorically as a body. The primary and the secondary bronchi only. For the further development of this "body" a series of "sacrifices" need to be carried out. These "sacrifices" are in truth the dichotomizations of the bronchial conduits that are necessary for the development of the bronchial tree and which will enable it to achieve the desired teleological endpoint. The ancient anatomists have imagined the pulmonary nerves as splitting and dividing the "primordial man" (virat purusa) and it is this conception that has been expressed (poetically) in various passages of the ancient texts such as Purusa Sukta, the creation hymn of the Rg Veda.

This sacrifice of purusa is similar to the development of an embryo. In so far as the respiratory apparatus is a philosophical model meant to illustrate certain general principles, it can also indicate the process of division or differentiation that goes on during the period of organogenesis. The growth of the bronchial tree through this process of sacrifice (dichotomization) thus reflects the growth of the embryo.

 

March of the Conduits: the Teleological Interpretation

 From the teleological standpoint, the march of the bronchi and the bronchioles in lockstep with the p. arterial and venous conduits reflects how disparate entities are steered by an intelligent mind towards a definite teleological end. The acinus represents the fructification of this teleological effort where the intelligence of the supreme mind culminates in a grand closure with the actual realization of the desired functionality. No wonder the dance of Krsna along with the gopis is so celebrated; because it represents the joyous culmination of God's teleological effort, expended for the welfare of the jiva.

Different Conceptions of Development Signified by Movements along the Bronchial Tree

The movement from the proximal to the distal portions (relative to the root) of the bronchial tree may be interpreted as the general evolution and development of the entire universe; from the first evolute (mahat) of nature signified by the primary bronchus, containing within it all possibilities and forms in latent form; and the gradual march from it towards diversification and the multiplicity of particular substances.
On the microcosmic level, this would represent the development of the body from the initially undifferentiated state of an embryo. The cells in the embryo seem to divide in the same pattern as the bronchial conduit. The progression is the same; 2, 4, 8, 16, 32, etc.
The movement in the opposite direction i.e. from the level of the alveoli and the respiratory bronchioles, may also be interpreted as a movement of creation--pertaining to the development of a particular product, the brain for instance. It shows how through the integration of simpler products and ultimately parts and particles, a particular product is built.
In the specific context of the bronchial tree, the unfurling of the world-lotus which is looked upon as the movement of creation, may, when considered in conjunction with the accompanying vasculature, also represent the gradual "burning up" and destruction of the world. Seen in this light, every creation, in a sense, is also a process of destruction. And the conventional movement of involution and winding up of the world may in a certain light be also the movement of creation;  when the integration of the bronchial conduits is considered along with the "clumping" and "coagulation" of the p. vein.

The Acinus in the Puranas

 The acinus is treated as a very special zone by the Puranic authors. These authors, endowed with the extraordinary skill of converting bare anatomical facts into easy to understand conceptions for the masses, were extra-conscious of the need to reflect the difference between the conducting and the respiratory portions of the lung in their metaphorical narrative.

A Great Center of Production

The acinus which is the functional zone of the lung is regarded as a center of production by these great wizards of metaphor. As is evident from the description of Puskaradvipa, it is the region  of plenty a veritable cornucopia, where there is an abundance of foodgrains and riches and the objects of sense enjoyment. For the neural entities and the entities of the microcosm, it is the flow of oxygen molecules alone that constitutes the supreme object of desire. It is the fruit of every sacrifice, the objective behind every effort and the supreme wealth and treasure. 

In addition to the metaphor of the gold mine one other metaphor applied to the acinus is that of the crops. The clusters of respiratory bronchioles are viewed as the region of foodgrains such as paddy. The grains processed from these fields which again stands for the life-sustaining flow of oxygen-rich blood, is sent via channels of food--the pulmonary veins--for storage in the left atrium and eventual distributon among the neural entities as rice. This giving or bestowing is done by the aorta (Laksmi's abode) through the medium of the bronchial arteries. 

Speaking of Krsna, the most famous metaphor applied to the region of the acinus is Gokula, the station of cows. The lila of Krsna is the exercise of the Lord's conscious intervention in the most distal region of the lung where true respiration takes place, the acinus. The conscious power of the Lord is exercised at each and every level of the hierarchy.

Now, the Lord, in order to steer matter towards the desired teleological end, must intervene at each and every level of material development. At the level of the acinus the intervention of the Lord is perhaps at its most intelligent level. He has to integrate all the three chief entities of the pulmonary apparatus at this level.