Cell Injury: Intracellular and Extracellular Accumulations and Post Mortem Change

Question 1

what are 5 normal substances that accumulate in tissues?

Answer 1

1. lipids: called fatty change
2. lipofuscin: brown, granular breakdown products of lipids that indicate a cell is old or has been chronically injured
3. melanin: normal in dark tissues
4. bilirubin: increase in liver cells with decreased function because cannot export it
5. iron: from RBC breakdown

Question 2

what are 2 abnormal substances that accumulate within cells?

Answer 2

1. lysosomes fill with things that can’t be degraded; VERY BAD
2. viral inclusion bodies

Question 3

describe 3 postmortem color changes

Answer 3

1. hemoglobin imbibition: hemoglobin leaks out of autolyzed blood vessels, staining the surrounding tissue RED; can appear as feathering around blood vessels or if animal has been dead longer will appear as diffuse staining of tissues to look uniformly pink or red
2. pseudomelanosis: bacteria replicating postmortem in the INTESTINE an produce hydrogen sulfide which combines with the iron in hemoglobin to form iron sulfide which is BLACK, stains surrounding tissues black
3. bile imbibition: bile leaks out of gallbladder, staining surrounding tissues GREEN

Question 4

describe lipid accumulation (fatty change or hepatic lipidosis) (3)

Answer 4

1. fat vacuoles in cells other than adipocytes
2. 3 major causes:
   -overload of liver with free fatty acids (starvation, diabetes, diet)
   -inability of liver to conjugate with protein (starvation, toxins)
   -decreased utilization of FFA along pathways other than TG synthesis (anemia)
3. this is reversible but function can be impaired if severe

Question 5

describe melanin accumulation

Answer 5

melanosis: melanin deposited in abnormal locations (like liver or lung); is not neoplastic and does not interfere with function but will cause affected meat to be condemned

Question 6

describe bilirubin accumulation (2)

Answer 6

1. when mucous membranes are discolored, the CONDITION is called icterus, suggesting problems with hemolysis or liver function
2. color is due to the pigment bilirubin, a breakdown product of hemoglobin

Question 7

describe hemosiderosis (iron) accumulation (3)

Answer 7

1. in cases of congestive heart failure, blood backs up into the lungs and is phagocytized by macrophages
2. when enough iron accumulates in macrophages, the lungs can appear brown (from hemosiderin)
3. when hemosiderin is present in large amounts, the condition is called hemosiderosis

Question 8

describe viral inclusion body deposits (2)

Answer 8

1. when viruses replicate in cells, the can produce so much nucleic acid that it forms a rounded mass that can be seen histologically
2. can be from infectious canine hepatitis, rabies, and canine distemper virus

Question 9

describe amyloidosis (an extracellular accumulation)

Answer 9

1. a disease of abnormal protein folding
2. serum amyloid A (SAA) is the most common cause of amyloidosis in animals! SAA is an acute phase reactant produced by the liver to modulate inflammatory reactions
3. AL amyloidosis can occur from overproduction of immunoglobulin light chains, getting misfolded and deposited as amyloid
4. islet amyloid polypeptide (IAPP) amyloidosis occurs when IAPP, normally deposited in the islets of Langerhans in the pancreas are misfolded; often due to diabetes mellitus
5. renal amyloidosis: in renal glomeruli, severely affects renal function
6. alzheimer’s disease and hyperthyroidism also cause amyloid deposition
7. not reversible!!!