It will not be out-of-place here to mention a word on lungs and their functions. The organs of respiration consist of two lungs, one on either side of the chest and the air passages that lead to them. They are located in the upper thoracic cavity of the chest, one on each side of median line. They are separated from each other by the heart, the greater blood vessels and the larger air-tubes. The lungs are spongy, porous and their tissues are very elastic. The substance of the lungs contains innumerable air-sacs, which contain air. After post-mortem, when it is placed in a basin of water, it floats. They are covered by a delicate serous membrane called the pleura which contains serous fluid to prevent friction of the lungs, during the act of breathing. One wall of the pleura closely adheres to the lungs. The other wall is attached to the inner wall of the chest. Through this membrane the lungs are fixed to the wall of the chest.
The right lung consists of three lobes.The left lung contains two lobes. Each lung consists of an apex and a base. The base is directed towards the diaphragm, the muscular septum, the dividing wall between throat and abdomen. The apex situated above, near the root of the neck. It is the base that gets inflamed in Pneumonia. The apex of the lung which does not get proper supply of oxygen gets affected by consumption. It affords favorable nidus or breeding ground for Tubercle Bacilli (T.B.). By the practice of Kapalabhati and Bhastrika Pranayamas and deep breathing exercises, these apices get good supply of oxygen and thus phthisis is obviated. Pranayama develops the lungs. He who practices Pranayama will have a powerful, sweet, melodious voice.
The air-passage consists of the interior of the nose, pharynx or throat, larynx or the wind box, or sounding box, which contains two vocal cords, trachea or windpipe: right and left bronchi and the smaller bronchial tubes. When we breathe, we draw in the air through the nose and after it has passed through the pharynx and larynx, it passes into the trachea or windpipe, thence into the right and left bronchial tubes, which in turn, subdivide into innumerable smaller tubes called bronchioles, and which terminate in minute subdivisions in the small air-sacs of the lungs, of which the lungs contain millions. The air-sacs of the lungs when spread out over an unbroken surface, would cover, an area of 1,40,000 square feet.
The air is drawn into the lungs by the action of the diaphragm. When it expands, the size of the chest and lungs is increased and the outside air rushes into the vacuum thus created. The chest and lungs contract, when diaphragm relaxes and the air is expelled from the lungs.
The Science of Pranyama by Sri Swami Sivananda