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.

    18/34 (page 16)
    So much in the verification of theories connected with Physiology must depend on the way in which collateral facts are explained by them that it will be advisable now to consider some of them, and these considerations will be divided into two sections,— 1st. The explanation of the known variations in pulse rate in health, and 2ndly, The explanation of the cardiograph laws. 1st. Variations in Pulse rate in Health. With re- gard to these points, as on this theory change in pulse rate can only depend on change in arterial resistance it is evident that Marey's law will, upon his supposition as to the relation between blood pressure and arterial resistance, explain the pheno- mena equally well. The following are some of the best known : The effects of Respiration on the Pulse rate. Physiologists, though not completely agreed as to the effects of respiration on the pressure of the blood in the arteries, all acknowledge that during inspiration the pulse quickens, and during ex- piration it gets slower, whether the pressure rises or falls. The theory under consideration clearly shows that this must be so, for during inspiration the expansion of the chest must reduce the pressure in the intra-thoracic aorta, and consequently its contained blood must fall in tension more rapidly than if the chest were motionless, and the more rapid tension fall causes increase in pulse rate. In expiration the opposite occurs, diminution in chest capacity reduces the size of the aorta and conse- quently delays the time of fall of tension and there- fore slows the pulse.