Licence: In copyright
Credit: Arterial hypertonus, sclerosis and blood-pressure. Source: Wellcome Collection.
Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.
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![be assumed to be present in the blood, so affect its viscosity or specific gravity as to impede its flow through tlie arterioles and capillaries. In cliolera certainly, and probably in other conditions with great intestinal flux, the blood becomes so inspissated as to seriously impede its flow; but in such a condition as chronic interstitial nephritis, that there should be anything approaching this state is a very different matter. AVith a free supply of fluid it is difficult to think of the vLcosity of the blood, thereby meaning its specific gravity, being seriously modified, seeing that fluid is so readily taken iip and discharged from it. Huchard imlds that excess, and above all errors, in alimentation, throw toxic substances into tlie blood which produce a state of spasm ol the arterial system, followed by iiyper-tension and arterio-sclerosis. Senator and _ many others huld corresponding views with regard to the importance of the presence of nitro- genous^waste^^ in the blood. The general conce])tion undoubtedly is that “ nitrogenous waste, and the p>roducts of imperfect metabolism,” to repeat Broadbent’s words, when present in the blood, raise blood- pressure. It is not necessary to elaborate this point further: the literature of kidney disease, and more recently of blood-pressure, is full of it, not to go further afield for examples. The explanation of the raised blood-pressure has usually l)een referred to increased peripheral resistance, and there the matter has as a rule been left; although, as has been said, critical and accomplished physicians like Broadbent and Allbutt have seen that this term in tlie ecpiation wants determining, while to otliers the phrase in itself has been all-satisfying. My contention is tliat certain substances present in the_ blood, even in small quantity, cause arterial and capillary contraction. This is the fundamental fant. and will be found to be the first step in_ all raising of blood- pressure which goes on to arterio-sclerosis. Even a slight degree of such contraction means peripheral resistance. There is indeed no need to_gp Ij^mnd vascular contraction for the explanation of peripheral resistance; it is the simplest explanation, as it is the most certain factor, and,](https://iiif.wellcomecollection.org/image/b28036591_0065.jp2/full/800%2C/0/default.jpg)
