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Physiology of Breathing
he breath is the thing closest to us. It is tangible,
believable, understandable and controllable. The gentle inhalation and exhalation sustains us, calms us, affects our thoughts and is itself affected by our activities, emotions and thoughts. We all experience this daily, yet the breath is often ignored or forgotten. In the practices of pranayama, we become deeply familiar with the breath. A good knowledge of the respiratory system will, therefore, aid and enhance the practices, and help in a better understanding of their physiological parameters. It will also prove indispensable in practising prana vidya, when awareness must be focused on specific internal body parts.
Respiratory structure The human torso is divided into three parts: the thorax or chest cavity, which houses the heart and lungs; the abdomen which is separated from the thorax by a thin muscle called the diaphragm, and contains the organs of digestion; and the pelvis, which extends from the hip bones to the perineum, and contains the organs of excretion and reproduction.
The lungs and heart are contained in the ribcage or thoracic cavity, a cage of bones, cartilage and muscles. The lungs themselves are passive. They inflate and deflate only because the walls and floor of the thoracic cavity move, pumping the air in and out of the lungs. The boundaries of the thorax are
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