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Respiration is an automatic, involuntary process, being regulated according to the body’s internal needs. With healthy lungs, we breathe normally and rhythmically, yet unconsciously, as the process is beyond our conscious control. At rest we breathe slowly and less deeply. As activity is increased, breathing becomes more rapid, with greater excursions of the diaphragm and chest to allow for increased oxygen intake.
 
Respiration is an automatic, involuntary process, being regulated according to the body’s internal needs. With healthy lungs, we breathe normally and rhythmically, yet unconsciously, as the process is beyond our conscious control. At rest we breathe slowly and less deeply. As activity is increased, breathing becomes more rapid, with greater excursions of the diaphragm and chest to allow for increased oxygen intake.
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But the respiratory movements are not confined to the chest alone; they are systemic motions pervading the whole trunk. It is known that the rhythmic pulsations of the heart synchronize with the movements of the chest in respiration. These breathing movements also constitute an important factor in the circulation of the blood, as we may experience
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But the respiratory movements are not confined to the chest alone; they are systemic motions pervading the whole trunk. It is known that the rhythmic pulsations of the heart synchronize with the movements of the chest in respiration. These breathing movements also constitute an important factor in the circulation of the blood, as we may experience in the case of a drowned person being resuscitated by artificial respiration, by which circulation and heart action are restored.
 
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in the case of a drowned person being resuscitated by artificial respiration, by which circulation and heart action are restored.
      
By far, the largest organs in the body are the lungs, designed and adapted to their work of receiving air and nothing else. They fill the thorax from the collarbone to the lowermost ribs and from the sternum in front to the spine in back. When the chest wall is raised through the action of the muscles of the chest, and when the diaphragm is depressed, the chest cavity expands, this forms a vacuum, and the air rushes into it. Conversely, when the chest wall contracts and the diaphragm is raised, the air is forced out of the lungs. Coincidentally with this process, the blood flows through the lungs, picking up oxygen, carrying it to the ceils and giving off carbon dioxide that it has brought from the cells. This whole process is automatic and is regulated by the body’s need for oxygen.
 
By far, the largest organs in the body are the lungs, designed and adapted to their work of receiving air and nothing else. They fill the thorax from the collarbone to the lowermost ribs and from the sternum in front to the spine in back. When the chest wall is raised through the action of the muscles of the chest, and when the diaphragm is depressed, the chest cavity expands, this forms a vacuum, and the air rushes into it. Conversely, when the chest wall contracts and the diaphragm is raised, the air is forced out of the lungs. Coincidentally with this process, the blood flows through the lungs, picking up oxygen, carrying it to the ceils and giving off carbon dioxide that it has brought from the cells. This whole process is automatic and is regulated by the body’s need for oxygen.