The Lumleian lectures on the muscular arterioles : their structure and function in health and in certain morbid states : delivered at the Royal College of Physicians / by George Johnson.

  • Johnson, George, 1818-1896.
Date:
1877
Catalogue details

Licence: Public Domain Mark

Credit: The Lumleian lectures on the muscular arterioles : their structure and function in health and in certain morbid states : delivered at the Royal College of Physicians / by George Johnson. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    add to the work of the ventricle in a greater degree than the degenera- tion and impaired elasticity of the large arteries. In the advanced stages of renal degeneration, some of the muscular arterioles may undergo degenerative changes, partly perhaps due to the impure blood which they transmit, and partly to the excessive strain to which they are subjected by the forcible contraction of the hypertro- phied heart. In the so-called lardaceous form of renal disease, the muscular arterioles very early undergo this degenerative change, and, their contractile power being thus impaired, they are unable to regulate or to impede the circulation. Hence it happens that hypertrophy of the heart is rarely associated with this lardaceous form of disease. Amongst the accidental injuries which result from the high arterial tension associated with renal disease, one of the most frequent and most serious is the occurrence of rupture of one or more intracranial arteries, and consequent haemorrhage into the substance or on the surface of the brain. It has been a debated question with some writers on cere- bral haemorrhage, whether the occurrence of that accident is favoured by hypertrophy of the left ventricle. When hypertrophy of the heart is a result of disease of the aortic valves, or of degeneration with im- paired elasticity of the walls of the large arteries, it is generally no more than sufficient to overcome the impediment thus offered to the circulation. The strength of the left ventricle, therefore, in such cases is not a true measure of the force with which the blood is sent into the distal arteries. On the contrary, it is a measure of the difficulty with which the blood is transmitted through the primary branches, and, therefore, through the entire system of arteries. When hypertrophy, thus originating, is associated, as it sometimes is, with cerebral haemor- rhage, the reason is that the hypertrophy and the haemorrhage are joint results of one common cause, namely, degeneration pervading more or less extensively the arterial tree. The hypertrophy of the left ventricle is a consequence of degeneration of the aorta and its primary branches. The cerebral haemorrhage is a consequence of a similar degeneration of the arteries of the brain. The state of the circulation is very different when the left ventricle has become hypertrophied, in consequence of the impediment resulting from contraction of the hypertrophied muscular arterioles in connection with degeneration of the kidney. In this state of things, while the arterial stopcocks are resisting the passage of the morbid blood, the strong left ventricle is forcibly driving it onwards. There is thus an excessive strain upon the whole length of the arterial pipes, between