INFLAMMATION. 167 



335. Effects which result in the neighbouring parts from the stagnation of 

 the circulation at the inflamed part. 



But around the inflamed part there is an undue and unusual accumu- 

 lation of blood. This accumulation is not in itself primarily a disease. 

 It is simply the mechanical result of the stagnation of the blood at the 

 inflamed part. The heart continues in its usual state of activity, and 

 propels the blood forward through the various channels of the circula- 

 tory system : but the blood, which would in due time come to and pass 

 through the inflamed part, is necessarily arrested by the stagnation and 

 congestion, which has already taken place at the seat of the disease, and 

 consequently the vessels around the stagnation are dilated, and contain 

 more blood than natural. As the current of blood continues to flow into 

 the neighbouring parts, the vessels become more and more overloaded, 

 congested, and dilated. Hence also the strong and heavy throbbing felt 

 in the arteries leading to the part. 



It is not, however, to be supposed that there is complete arrest of the 

 circulation in those parts. The vessels surrounding the inflamed part, 

 with their innumerable ramifications, enlarge, and thus permit to pass 

 through them a considerable portion of the blood which in health would 

 pass through the vessels at the original seat of the disease. The vessels 

 on the sides may, however, become so much paralysed from over-disten- 

 sion that their contents also may almost cease to flow, and thus the area 

 of the disease may become extended. 



As, however, the seat of the inflammation is usually among the capil- 

 laries, which have innumerable ramifications in every direction, the 

 check on the circulation is less than might at first sight have been 

 expected, because collateral circulation is so readily established. 



The undue accumulation of blood thus arising we shall hereafter term 

 " Hyperoemia." 



336. Effect of inflammation on the general circulation. 



The general circulation is but little affected. The hypersemia in the 

 surrounding parts is due to the simple mechanical cause detailed above. 



If, however, Fever supervenes, as it usually does in all serious and 

 extensive attacks, the circulation will be quickened, sometimes to an 

 excessive degree. 



337. Fever. 



If the hyperasmia be excessive, or if the pain attending the original 

 attack of inflammation be great, or if the patient be very irritable, or if 

 the part attacked be very sensitive, we may expect symptomatic Fever 

 to set in. 



Fever is general nervous irritability, from which arises a quickened 

 state of the circulation. The pulse in consequence is always affected to 

 a greater or less degree, and increased in frequency. The respirations 

 are increased, and so also is the heat of the body. Fever is generally 

 ushered in with shivering and accompanied with thirst. 



