It will not be out of place here to mention a word on lungs and their functions. The organs of respiration consists 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 the 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 contain 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. 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 is 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 favourable nidus or breeding ground for Tubercle Bacilli (T.B.). By the practice of Kapalabhati and Bhastrika Pranayama 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.
It is through vocal cords that are located in the larynx that sound is produced. Larynx is the sounding box. When the vocal cords are affected by too much straining, as in singing and continuous lecturing, the voice becomes hoarse. In females these cords are shorter. Hence they have a sweet melodious voice. The number of respiration per minute is 16. In pneumonia it is increased to 60, 70, 80 per minute. In Asthma, the bronchial tubes become spasmodic. They contract. Hence there is difficulty in breathing. Pranayama removes the spasm or constriction of these tubes. A small membranous flat cap covers the upper surface of larynx. It is called Epiglottis. It prevents the food particles or water from entering into the respiratory passage. It acts the part of a safety valve.
When a small particle of food tries to enter the respiratory passage, cough comes in and the particle is thrown out.
Lungs purify the blood. The blood starts in its arterial journey, bright-red and rich-laden with life-giving qualities and properties. It returns by the venous route, poor, blue-laden with the waste matter of the system. Arteries are tubes or vessels that carry pure oxygenated blood from the heart towards the different parts of the body. Veins are vessels or tubes that carry back impure blood from the different parts of the body. The right side of the heart contains impure venous blood. From the right side of the heart the impure blood goes to the lungs, for purification. It is distributed among the millions of tiny air-cells of the lungs. A breath of air is inhaled and the oxygen of the air comes in contact with the impure blood through the thin walls of the hair-like blood-vessels of the lungs called pulmonary capillaries. The walls of the capillaries are very thin. They are like muslin cloth or sieve. Blood oozes out or exudes readily. Oxygen penetrates through the walls of these thin capillaries. When the oxygen comes in contact with the tissues, a form of combustion takes place.
The blood takes up oxygen and releases carbonic acid gas generated from the waste products and poisonous matter, which has been gathered up by the blood from all parts of the system. The purified blood is carried by the four pulmonary veins to the left auricle and thence to the left ventricle. From the ventricle it is pumped into the biggest artery, aorta. From aorta, it passes into the different arteries of the body. It is estimated that in a day 35,000 pints of blood traverses the capillaries of the lungs for purification.
From the arteries the pure blood goes into the thin capillaries. From the capillaries the lymph of the blood exudes, bathes and nourishes the tissues of the body. Tissue respiration takes place in the tissues. Tissues take up the oxygen and leave the carbon dioxide. The impurities are taken by the veins to the right side of the heart.
Who is the creator of this delicate structure? Are you feeling the invisible hand of God behind these organs? The structure of this body bespeaks undoubtedly of the omniscience of the Lord. The Antaryamin or the Indweller of our hearts supervises the working of the inner factory as Drashta. Without His presence, heart cannot pump blood into the arteries. Lungs cannot carry out the process of purifying the blood. Pray. Pay your silent homage to Him. Remember Him at all times. Feel His presence in all the cells of the body.