The laws and mechanics of circulation, with the principle involved in animal movement . ory force in the lungs for speedingthe blood into the plexuses. Hence, the rise in arterialpressure during inspiration, together with the increasedrhythms in the heart and vessels, as indicated in the trac-ings (Fig. 40, 3); which is plain enough, the increased actionin the heart, the rise in arterial pressure, and the fall inintra-thoracic pressure. But during expiration and thedevelopment of high pressure in the alveoli, which this pro-duces, the arterial system expands for receiving the blood 134 PHYSIOL
The laws and mechanics of circulation, with the principle involved in animal movement . ory force in the lungs for speedingthe blood into the plexuses. Hence, the rise in arterialpressure during inspiration, together with the increasedrhythms in the heart and vessels, as indicated in the trac-ings (Fig. 40, 3); which is plain enough, the increased actionin the heart, the rise in arterial pressure, and the fall inintra-thoracic pressure. But during expiration and thedevelopment of high pressure in the alveoli, which this pro-duces, the arterial system expands for receiving the blood 134 PHYSIOLOGICAL PEOBLEM ELUCIDATED. which pours into it during this time from the plexuses, thereby-reducing resistance to the inpour of blood from the heart andobviating strain to the organ, since room must be made for theblood; hence the fall in arterial tension, which continues oninto the earlier portions of inspiration (e. i., 2, 4, 5). In thismanner, then, the large undulations in arterial pressure syn-chronous with respiration (2, 2) are formed, two of them pre-senting in the Pig. 40.— Comparison of Blood-Pressure Curve, with Curve of Intra Thoracic be read from left to right. The figures are added.—Foster, a, blood-pressurecurve, with its respiratory undulations, the slower beats on the descent being verymarked ; b, curve of intra-thoracic pressure obtained by connecting one limb of amanometer with the pleural cavity. Inspiration begins at <, expiration at e. Theintra-thoracic pressure rises very rapidly after the cessation of the inspiratory effort,and then slowly falls as the air issues from the chest; at the beginning of the inspira-tory effort the fall becomes more rapid. But while this action is going on in the arterial system, therhythms in the heart and arteries are altered correspondingly,being increased in frequency during inspiration (3, i, e) byhurrying the systoles and shortening the diastoles, the oneinvolving the other, the object being
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Keywords: ., bookcentury1800, bookde, booksubjectblood, booksubjectrespiration
