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By Root 616 0

lungs expand, with outward chest movement, in the thoracic phase as inhalation proceeds further. At the very end of inhalation, still more air is admitted by slightly raising the clavicles, thereby expanding the uppermost tips of the lungs. In sequence, then, each phase of inhalation acts on one particular area of the lungs.”7 As we shall see, no matter what state we may be in, most of us depend mainly on chest and clavicular breathing, and have little experience of diaphragmatic breathing. Thus, we seldom draw air into the deepest areas of our lungs, where most of our blood awaits oxygenation.

Figure 4

THE INNER BREATH

Whatever outer form our breath takes, an inner process of breathing also occurs. This process takes place in the cells, which inhale oxygen from the steady stream of hemoglobin flowing throughout the body and exhale carbon dioxide back into this stream. It is in the cells, and more particularly the mitochondria, where the inhaled oxygen helps transform food into biological energy. This transformation occurs when oxygen is combined with carbon (from food) in a slow-burning fire. The energy released from the interaction of oxygen and carbon is transferred to energy storage molecules, called ATP (adenosine triphosphate), which make it available to all the cells of the body. Waste products, such as carbon dioxide, are returned to the venous blood and ultimately to the lungs and back into the atmosphere.

THE RESPIRATORY CENTER

The process of breathing and its relationship to the production of energy in our organism is so fundamental to our survival that nature has given us little direct control over it. Our breathing is thus mostly involuntary, generally controlled by the respiratory center of the autonomic nervous system—especially the vagus nucleus in the medulla oblongata, the nervous tissue at the floor of the fourth ventricle of the brain (Figure 5). The respiratory center, which is located near the occiput (where the spine meets the skull), transmits impulses to nerves in the spinal cord that cause the diaphragm and intercostal muscles to begin the process of inhalation. Branches of the vagus nerve coming from this center sense the stretching of the lungs during inhalation and then automatically inhibit inhalation so that exhalation can take place. The respiratory system is connected to most of the body’s sensory nerves; hence any sudden or chronic stimulation coming through any of the senses can have an immediate impact on the force or speed of our breath, or can stop it altogether. Intense beauty, for example, can momentarily “take our breath away,” while pain, tension, or stress generally speeds up our breathing and reduces its depth. We can, of course—within limits—intentionally hold our breath, lengthen or reduce our inhalation and exhalation, breathe more deeply, and so on. When we do so, the nerve impulses generated in the cerebral cortex as a result of our intention bypass the respiratory center and travel down the same path used for voluntary muscle control.

Figure 5

Acid/Alkaline Balance

The respiratory center does its work based on the acid/ alkaline balance of the blood. The cells in the nucleus of the medulla are sensitive to this balance. From the standpoint of our health, the blood must remain slightly alkaline (pH 7.4). Even tiny deviations from this condition can be dangerous. When the body’s chemical activity increases because of physical effort, emotional stress, sensory stimulation, and so on, more carbon dioxide and other acids are produced. This increases the acidity of the blood. To counteract this increase and maintain homeostasis, the respiratory center automatically increases the breath rate. This helps to bring in needed oxygen and to expel excess carbon dioxide. When the body’s chemical activity decreases through relaxation or rest, less carbon dioxide is produced and our breathing automatically slows down.8

Though we cannot, for the most part, alter the basic chemistry of the respiratory process, we can influence it in a variety of “indirect” ways.