On the law which regulates the frequency of the pulse / by A. H. Garrod, B.A.

  • Garrod, Alfred Henry.
Date:
1872
Catalogue details

Licence: Public Domain Mark

Credit: On the law which regulates the frequency of the pulse / by A. H. Garrod, B.A. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    the circulation, as they appear to me, may assist in explaining some of the previous arguments. The circulation of the blood is maintained by the repeated contraction of the heart. Each cardiac revolution is divided into three parts, the systole, the diaspasis, and the diastole. The following laws hold with regard to the length of these intervals. I. The systole together with the diaspasis, or in other words, the first cardiac interval varies as the square root of the whole revolution. IL The systole varies as the square root of the diastole. III. The diaspasis is constant. The amount of work that the heart has to perform in maintaining the circulation depends on two sets of changes which may occur in the system; i. Variations in the blood pressure. 2. Variations in the resistance to the outflow of that fluid from the arteries. As the capacity of the arteries including the ventricles, varies directly as the blood pressure, and as the flow of blood from the capillaries does the same, the frequency of the heart's beats is dependent on the resistance to the capillary ouU flow, and not at all on the blood pressure ; in other words, the heart always recommences to beat when the blood pressure in the systemic arteries has. fallen a certain invariable proportion. Variations in blood pressure result from : i. Ab- sorption into, and excretion from the vascular sys- tem, of fluids. 2. Changes in the capacity of the arterial system, which occur on the contraction or