|[ Excerpt from The Science of Yoga, page 57 ]
The respiratory system is a marvel of evolutionary engineering. Its function is the heart of existence for mammalian life forms.
From a biological perspective, modern science has painted a broad picture of its function, yet much remains to be discovered about its deeper dimensions and purpose. From a purely biological viewpoint though, we can gain some understanding of some of the imperatives of our pranayama practice.
The lungs are two sponge-like organs located in the thoracic (chest) region, which are responsible for respiration.
When we say respiration, we need to consider not only the mechanical nature of breathing in (inspiration) and breathing out (expiration), but also the mechanism for absorption of the vital nutrients from the inhaled air into our organism, as well as the expulsion of wastes on the exhalation.
The lungs are situated, one on either side of the chest, the left lung itself being of a somewhat smaller size so as to accommodate the heart, which also lies primarily on the left side within the thorax. The right lung is divided into three distinct sections or 'lobes'.
The left lung, because of the impeding location of the heart, has only two separate lobes. The lungs are enclosed in a protective sack called the pleura, as is the heart (within the pericardium).
The base of the lungs rest upon a large, membranous-like muscle called the diaphragm, which forms the entire inferior aspect, or base of the thoracic cavity. It has its attachments along the entire lower margins of the ribs, both front and back, and plays a vital role in the action of breathing.
From a medical standpoint, it is the oxygenation of the blood (oxygen taken from inhaled breath) and the elimination of waste products from the bloodstream (carbonic acid released in the exhaled breath) that is the primary function of the lungs.
The interior of the lungs themselves house over an astounding 600 million cells which, if they were to be laid out over a flat surface, would cover an area greater than the size of a football field! It is this labyrinth of cells that provide the vehicle for absorption of the nutrients in the air we breathe - that vital energy prana...
NOTE: This yoga article is an excerpt from The Science of Yoga, an online yoga training program with streaming yoga videos and 600 pages of step-by-step yoga instruction.
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