INFLAMMATION. 1/3, 



are not inflammatory exudates. Inflammati.m of mucous mem- 

 branes m which there is an excessive production of mucus is 

 catarrh or catarrhal inflammation. (Suppuration is mflammation 

 accompanied by the formation of pus and may be surface or sub- 

 surface. Purulent inflammation is surface suppuration.) 



ri.yof!/r.— Histologically a gland or organ is composed of 

 parenchymatous and interstitial tissue. Parenchymatous tissue 

 is the essential or functioning portion of a structure, as hepatic 

 cells. Interstitial tissue or stroma is the supporting framework 

 of an organ or part as the stroma of a lymph node. The pro- 

 cess of inflammation may occur in either the parenchyma or 

 stroma. Classifying upon the basis of tissue aft'ected then, there 

 are the two forms, namely, parenchymatous and interstitial in- 

 flammation. 



(a) Parenchymatous inflammation is usually the result of 

 severe, active irritati(m, the interstitial type results from the 

 long, continued action of mild arritants. The two tvpes mav be 

 present simultaneously in the same structure or they may occur 

 independently. 



(b) Interstitial inflammation is often the sequence of paren- 

 chymatous, although it may be the initial process. Inflammation 

 of the hepatic cells is parenchymatous hepatitis, of the hepatic 

 interlobular tissue, interstitial hepatitis, etc. 



Tunc, Activity and Results of the Process. — It is questionable 

 if the length of time an inflammatory process continues sliould 

 constitute a factor in its classification. Bv common usage, inflam- 

 mation would be classified according to the time basis, as acute 

 and chronic. Formerly this classification was based upon the 

 time element alone, but the duration of inflammation is so vari- 

 able that it is now recognized as an insignificant factor. The 

 activit^' and results of the process are the basic essentials relied 

 upon in differentiating acute and chronic inflammation. 



(a) Acute inflammation is characterized bv a sudden onset, by 

 a vigorous action and by production of retrogressive changes in 

 or destruction to the tissue aft'ected. 



(b) Chronic inflammation is characterized usuallv by an 

 insiduous onset, by a mild action, and by resutling in prolifera- 

 tion of tissue. The proliferated tissue may induce retrogressive 

 changes, as atrophy, but this is only an indirect result of the pro- 

 cess. 



Either acute or chronic inflammation may occur throughout 

 the entire reaction or they may both prevail at the same time in 

 different parts of the same structure. The causative agents mav 

 become less active as the process continues, thus acute inflam- 



