Module 1

Question 1

Answer 1

Question 2

Answer 2

Question 3

Answer 3

Question 4

Answer 4

Question 5

Answer 5

Question 6

Answer 6

coagulative necrosis

• microscopic view of the edge of the infarct, with normal kidney and necrotic cells in the infarct
  
  • the necrotic cells show preserved outlines with loss of nuclei
• the injury denatures not only structural proteins but also enzymes thereby blocking the proteolysis of the dead cells; as a result, eosinophilic, anucleate cells may persist for days to weeks
• coagulative necrosis is characteristic of infarcts (areas of ischemic necrosis) in all of the solid organs except the brain

Question 7

Answer 7

liquefactive necrosis

• liquefactive necrosis is seen in bacterial infxns because microbes stimulate the accumulation of inflammatory cells and the enzymes of leukocytes digest (liquefy) the tissue
  
  • the dead cells are completely digested, transforming the tissue into a liquid viscous mass
  • eventually the digested tissue is removed by phagocytes
• mainly seen in the brain (CNS)

Question 8

Answer 8

fat necrosis

• the image shows fat necrosis in acute pancreatitis; the areas of white chalky deposits represent foci of fat necrosis with calcium soap formation (saponification) at sites of lipid breakdown
• pancreatic enzymes (lipases) that have leaked out of acinar cells and ducts liquefy the membranes of fat cells in the peritoneum, and lipases split the triglyceride esters contained within fat cells
  
  • the released fatty acids combine with calcium to produce grossly visible chalky white areas (fat saponification)

Question 9

Answer 9

fibrinoid necrosis

• in the image: fibrinoid necrosis in an artery
  
  • the wall of the artery shows a circumferential bright pink area of necrosis with protein deposition and inflammation
• usually caused by immune reactions in which complexes of antigens + antibodies are deposited in the walls of arteries
  
  • the deposited immune complexes, together with fibrin that has leaked out of vessels, produce a bright pink and amorphous appearance

Question 10

Answer 10

chronic granulomatous inflammation

• epitheloid histiocytes (macrophages with abundant pink cytoplasm are the defining feature of granuloma
• granulomatous inflammation is a distinctive pattern of chronic inflammation characterized by aggregates of activated macrophages with scattered lymphocytes
  
  • can form with persistent T-cell responses to certain microbes (Mycobacterium tuberculosis, T. pallidum)
  • develop in some immune-mediated inflammatory diseases, notably Crohn disease
• the formation of a granuloma “walls off” the offending agent
• caseous necrosis can lead to a central zone of necrosis
  
  • conditions without caseous necrosis (Crohn disease, sarcoidosis, foreign body rxns) are called non-caseating

Question 11

Answer 11

acute inflammation

• dominated by neutrophils, macrophages
  
  • chemotactic factors: C5a (most powerful), IL-8, LTB4, bacterial products
• dilated blood vessels: caused by histamine
• pain: caused by bradykinin and PGE2
• fever: caused by PGE2

Answer 12

Question 13

describe chronic inflammation

Answer 13