514 MATER i A MEDIC A AND THERAPEUTICS. 



us to illustrate the application of the measures just noticed, may 

 be summarised as follows : 



1. Disorders of the fluid secretion referable to the general blood 

 pressure. (a) Diminution of the general arterial pressure, which is 

 generally referable to heart disease, leads to marked disturbance 

 of the urinary flow. We saw under the head of the circulation 

 (page 472) how dilatation of the heart lowers the pressure in 

 the arteries and raises it in the veins, i.e. lowers it in the 

 afferent vessel of the glomerulus, and raises it in the efferent 

 vessel, thus causing congestion of the kidneys. The urine in this 

 class of cases contains albumen and blood proceeding from the 

 engorged veins ; it falls in quantity in consequence of the fall 

 in the arterial pressure, and of obstruction in the tubules, which 

 become choked with fibrinous casts ; and the total excretion of 

 solids is diminished, as the result of retardation of the blood 

 current. 



(b) Increase of the general arterial pressure is associated with 

 that form of chronic disease of the kidney known as the ' ' Granu- 

 lar or Contracted Kidney." Here the urine is very abundant, 

 probably reaching several times its normal volume, very light 

 in colour and weight, and may contain a trace of albumen. 

 The tension of the radial artery is high ; the left ventricle is 

 hypertrophied ; and the patient often dies of secondary dilatation 

 of the heart, or of rupture of an artery in the brain. As far as the 

 kidney is concerned, the condition is one of constant pathological 

 diuresis. 



2. Disorders of the fluid secretion, referable to the local blood 

 pressure. (a) Certain nervous conditions disturb the pressure in 

 the kidney by causing contraction or dilatation of the renal 

 vessels, and thus modifying the amount of urinary water. Such 

 a condition may be either central or local, direct or reflex. 

 Thus hysteria is attended by alternately profuse and deficient 

 flow of urine. Disease of the medulla and its neighbourhood 

 may give rise to profuse diuresis (diabetes insipidw), which has 

 been traced in other cases to disease of the renal nerves. Reflexly, 

 the chief cause of disturbance of the renal secretion is injury or 

 disease of the prostate or urethra, which may even lead to 

 iital suppression. 



b. Morbid conditions of the blood-vessels of the kidney, such as 

 disease of the glomeruli, arteries and veins, which constitute one 

 of the elements of Bright's disease, produce a variety of dis- 

 tui'bances in the volume and constitution of the urine, according 

 to their exact seat and degree. Pressure on the trunks of the 

 renal vessels by abdominal enlargements may also cause 

 serious disturbance of the renal circulation, with albuminuria, 

 haemorrhage, or even suppression of urine as the result. 



