GENERAL PATHOLOGY. 13 



INFLAMMATION 



May be defined as * the succession of changes which takes 

 place in a living tissue as the result of some kind of injury, 

 provided that the injury be insufficient immediately to destroy 

 its vitality ' (Sanderson). 



The phenomena of inflammation in vascular structures 

 comprise — 



1. Changes in the blood-vessels and circulation. 



2. Exudation of fluid and blood- cells from the vessels. 



3. Changes in the tissues affected. 



(1.) Changes in the Blood-vessels and Circulation. — The 

 first effect of inflammation is dilatation of the arteries. This 

 dilatation steadily increases for about twelve hours, affecting 

 chiefly the arteries, but also the veins. The capillaries are 

 but slightly affected. The blood-flow becomes accelerated at 

 first, and then in about an hour it becomes considerably re- 

 tarded, though the vessels still remain dilated. Pulsation 

 in the small arteries becomes manifest, and slowness of the 

 stream allows of the distinction of individual corpuscles in 

 the capillaries and smallest veins. 



The acceleration of the blood-flow is not a constant occur- 

 rence, and often subsides without the appearance of the other 

 phenomena of inflammation. The dilation, with diminished 

 velocity, however, is constant, and is the essential vascular 

 change in inflammation. As the blood-flow becomes retarded, 

 white blood-cells gradually accumulate in the smaller veins, 

 adhering to their walls, and some also stick in the capillaries. 



Thus the lumina of the veins become narrowed by layers 

 of white cells, among which there are no red ones ; the cir- 

 culation becomes slower and slower, and the red blood-cells, 

 with some white ones, accumulate in the capillaries. 



Eventually the blood-stream in the capillaries ceases, 



