Irreversible Cell Injury

Question 1

Irreversible cell injury occurrence

Answer 1

-if severe and persistent stimulus, causes irreversible injury and then cell death

Question 2

Cell death types

Answer 2

1. Necrosis
2. Apoptosis

Question 3

Necrosis

Answer 3

-death of cells and tissues in the living animal

Question 4

Point of no return/tipping point

Answer 4

-the point in necrosis where:
>inability to reverse mitochondrial dysfunction
>profound disturbances in membrane function (results in an increase of Ca++ into the cell)

Question 5

Events of necrosis

Answer 5

-Hypoxia, ischemia or membrane damage
>Lysosomal leakage= acid hydrolases activated and decrease pH in cytosol= further membrane damage
>leakage of cellular enzymes outside
>calcium influx
>inflammation

Question 6

Clinical significance and cellular damage

Answer 6

-CK and ALT (liver) will increase if there is cellular damage

Question 7

Gross changes in tissue (ex.rumen) during necrosis

Answer 7

-necrotic tissue= paler than would expect (decreased blood; cell death results in influx of fluid which results in dilation)
-dull/matte appearance
-friable
-well defined borders
-inflammatory response=redness

Question 8

Cytoplasmic changes of necrosis

Answer 8

-cell swelling
-eosinophilia (increased redness)
>loss of ribosomes
>denatured intracytoplasmic proteins
-calcification

Question 9

Nuclear changes of necrosis

Answer 9

-Pyknosis- cell nucleus gets smaller and condense
-Karyolysis- nucleus of cell dissolves and fades away
-Karyorrhexis -nucleus has exploded, fragments

Question 10

Coagulative necrosis

Answer 10

-preservation of the basic outline of the necrotic cell for a span of at least some days

Question 11

Gross appearance of coagulative necrosis

Answer 11

-pale, swollen, firm/turgid
-demarcated by hyperemia (line of red=increase blood flow)
-more friable than adjacent tissue

Question 12

Renal infarct

Answer 12

-tissue dies due to decrease blood flow, but can still identify the tissue = coagulative necrosis
**hypoxic cell death BUT Can be caused by ischemia or bacterial exotoxins, although ischemia most likely

Question 13

Why is basic structure preserved in coagulative necrosis?

Answer 13

-because mostly due to blood flow loss, but membranes are still intact and enzymes remain within
>coagulation of cytoplasmic proteins including lysosomal enzymes

Question 14

Sequestrum

Answer 14

-fibrous capsule ring used to wall off the coagulation necrosis= indicates chronic coagulative necrosis

Question 15

Liquefactive necrosis

Answer 15

-focal pyogenic (pus forming) bacterial infections
>microbes attract neutrophils
>proteolytic enzymes liquefy the tissue

Question 16

Malacia

Answer 16

-liquefactive necrosis in the brain= hypoxic death of cells in CNS

Question 17

Abscess

Answer 17

-fibrous ring surrounding liquefactive necrosis= chronic

Question 18

Caseous necrosis

Answer 18

-necrosis in foci infected with mycobacterium, corynebacterium

Question 19

Caseous necrosis appearance

Answer 19

-grossly cheesy, white, and dry (like cottage cheese)
-microscopically: amorphous granular debris with calcification enclosed within granulomatous inflammation =MACROPHAGES
*tissue architecture=completely obliterated

Question 20

Granuloma

Answer 20

-fibrous ring surrounding caseous necrosis =chronic