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Module 4 Week 1 > Irreversible Cell Injury 3 - Necrosis > Flashcards

Irreversible Cell Injury 3 - Necrosis Flashcards

1
Q

5 types of necrosis

A
  1. Coagulative necrosis
  2. Liquefactive necrosis
  3. Caseous necrosis
  4. Gangrenous necrosis
  5. Enzymatic necrosis
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2
Q

-Coagulative necrosis
-_________ induced in what organs
-basic tissue preserved or not?

A

Ischaemia/toxin in liver, heart, kidney, skeletal muscle
Preserved temporarily

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3
Q

Liquefactive necrosis
____________ induced in CNS

A

Ischaemia/toxin

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4
Q

Caseous necrosis
Caused by…
Causes…

A

Mycobacteria infections like Tuberculosis
Causes tissues to become “cheese-like” in appearance

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5
Q

What changes do we recognise with cell death under the microscope?

A

—cytoplasmic changes
—nuclear changes

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6
Q

Cytoplasmic changes in the morphology of cell death
—early phase

A

Early phase:
-Cytoplasm becomes homogeneous pink in H&E section
Increased eosinophilia due to: loss of RNA which is responsible for cytoplasmic basophilia so basophilia lost
-condensed cytoplasm
-degradation of cytoplasmic proteins causes ghost-like appearance
-necrotic cells become “ individualised” i.e lose adherence/attachment to basement membranes and adjacent cells

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7
Q

Cytoplasmic changes in the morphology of cell death

—late phase

A

Cell membrane rupture with loss of integrity and release of cell contents into extracellular space

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8
Q

Name the 4 Nucleur changes in morphology of cell death

A

-Pyknosis
-Karyorrhexis
-Karyolysis
-Absence

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9
Q

Describe nuclear change of Pyknosis in cell

A

Shrunken, dark, homogenous, round, basophilic nuclei

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10
Q

Describe nuclear change of Karyorrhexis of cell

A

Fragmentation of nucleus
-rupture of nuclear membrane and chromatin
-dark nuclear remnants released into cytoplasm

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11
Q

Describe nuclear change of Karyolysis of cell

A

Nucleus becomes very pale
-due to dissolution of chromatin by DNAses

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12
Q

Describe the nuclear change of Absence of cells nucleus

A

Completely dissolved or lysed nucleus

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13
Q

Diagram of the different nuclear changes of cell during cell death

A

https://www.google.co.uk/url?sa=i&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FKaryolysis&psig=AOvVaw01aar9gkKfkmEcpPTUQp2I&ust=1674673524348000&source=images&cd=vfe&ved=0CA8QjRxqFwoTCMDljpbz4PwCFQAAAAAdAAAAABAg

https://www.google.co.uk/imgres?imgurl=https%3A%2F%2Fi0.wp.com%2Fwww.pathologystudent.com%2Fwp-content%2Fuploads%2F2022%2F08%2FNuclear-changes.png%3Fresize%3D655%252C212%26ssl%3D1&imgrefurl=https%3A%2F%2Fwww.pathologystudent.com%2Fdoes-pyknosis-occur-in-necrosis-or-apoptosis%2F&tbnid=x82gbgAnzZirHM&vet=12ahUKEwiWgc7R8-D8AhWOsCcCHZDuBgIQMygDegUIARDBAQ..i&docid=6Lgk51fnFeGPWM&w=655&h=212&q=pyknosis%2C%20karyohsis%20and%20karyolitic%20cell%20diagrams&hl=en-gb&client=safari&ved=2ahUKEwiWgc7R8-D8AhWOsCcCHZDuBgIQMygDegUIARDBAQ

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14
Q

Common causes of Coagulative necrosis

A

Hypoxia- local loss of blood supply
Ischaemia
Bacterial or chemical toxins
Local actin of irritating substances

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15
Q

Causes for renal necrosis (kidney)

A

Plants—>
—Cattle: -oak, acorn
-Oxalate (rhubarb, sorrel, dock)
—Cats:- Easter lily
—Pigs:- redroot pigweed phenolic compounds)
—Dogs:- raisins/grapes

Heavy metals—> mercury, lead

Chemicals—> ethylene glycol

Therapeutic drugs—-> antibiotics & chemotherapeutics

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16
Q

Necrosis relating to infectious disease
-viral infections
-bacterial infections

A

Viral infections

Infectious Bovine Rhinotracheitis (IBR)
-Bovine Herpesvirus 1 (BHV-1)
Canine parvoviral enteritis
-Canine Parvovirus 2 (CPV-2)
Canine infectious hepatitis
-Canine Adenovirus 1 (CAV-1)

Bacterial infections

Tuberculosis (Mycobacteria)
-Mycobacterium tuberculosis, M. bovis, other
Salmonellosis (S. enterica, serotypes S. typhimurium, S. choleraesuis, S. dublin etc.)
Clostridial infections (Cl. perfringens, Cl. difficile, Cl. chauvoei, Cl. septicum, other…)

17
Q

Infectious Bovine Rhinotracheitis
-caused by…
-causes what?
-may also cause secondary bacterial infection which results in…

A

-Bovine Herpesvirus 1

-causes transient acute febrile illness with respiratory signs
-causes severe hyperaemia and focal necrosis of: trachea, larynx, nasal cavity pharynx and mucosae

-also may cause secondary bacterial infection which results in thick plaques of fibrinonecrotic exudate

18
Q

Canine parvovirus enteritis
-caused by what
-causes what

A

-caused by canine parvovirus-2
-causes segmental necrosis and haemorrhage of small intestine (with this might also see variable dilation of intestinal loops &
granular texture of serosal surface)

19
Q

Canine infectious hepatitis
-caused by what
-causes what

A

Caused by CAV1
Causes liver to be enlarged and friable; will see fibrin on capsular surface and over liver lobes. Liver has granular appearance on serosal surface. Gallbladder walls thickened by oedema

20
Q

Caseous necrosis
-what does dead tissue look like
-microscopic appearance;
-contains what
-examples

A

Dead tissue converted into a glandular, friable mass
-Resembles cottage cheese
● Microscopic appearance
– accumulation of fragmented / lysed cells with an amorphous granular appearance
– tissue architecture obliterated, no cell outlines visible
– dystrophic calcification often seen centrally
● Chronic lesions
– often associated with poorly degradable bacterial lipids
Classic examples
– TUBERCULOSIS
– Corynebacterium pseudotuberculosis in sheep

21
Q

Caseous lymphadenitis (CLA)
-in which animals
-causes
-caused by
-spread by…
-incubation period

A

Sheep/goats
-causes chronic suppurative lymphadenitis
-caused by Corynebacterium pseudotuberculosis
-spread by;
● Shearing wounds
– arthropod bites or contaminated dips
● Spread by ruptured abscesses, oral and nasal secretions
Incubation period; 3 months

22
Q

Liquefactive necrosis

A

-Specific for CNS
-caused by hypoxia or toxin induced by neuronal necrosis which causes liquefaction

23
Q

What is liquefaction?

A

partial or complete dissolution of dead tissue and transformation into a liquid, viscous mass

24
Q

Describe the process of Liquefactive necrosis occurring due to pyogenic bacteria

A

1.Recruitment of inflammatory cells (mainly neutrophils)

2.Release of lytic enzymes

3.Destruction of bacteria
+ degeneration & necrosis of neutrophils

4.ABSCESS (pus-filled cavity)
can be considered a type of liquefactive necrosis

25
Q

3 types of gangrenous necrosis

A

-Moist
-Dry
-Gas

26
Q

Moist gangrenous necrosis
-Caused by…
-Requires which type of bacteria to occur?

A

-Infarction
-ischaemic necrosis in extreme cases
-Liquefactive action of saprophytic bacteria (requires this bacteria)

27
Q

Moist gangrenous necrosis
-gross findings
-histological findings

A

Gross: Soft, moist, reddish-brown-black,
Variable gas bubbles, putrid smell

Histological: Coagulative necrosis + proliferating bacteria,
Liquefaction +/- gas bubbles

28
Q

Dry gangrene necrosis

A

Coagulation necrosis secondary to infarction with mummification (dehydration)
-occurs normally in the distal limbs, tails, ears, udder
-related to ingestion of toxins, or cold (frostbite)
-gross appearance: dry, black/brown

29
Q

Gas gangrene necrosis (malignant oedema)
-caused by…
-gross & microscopic appearance

A

-Caused by infections with anaerobic bacteria that are proliferating & producing toxins in tissues - bacteria introduced by penetrating wounds into muscle/subcutis

-tissue is dark red to black
-sero-haemorrhagic exudate
-gas bubble formation
-coagulation necrosis of muscle

30
Q

How are anaerobic bacteria introduced into cell during gas gangrene

A

By penetrating wounds into muscle/subcutis

31
Q

Example of gas gangrene necrosis

A

Blackleg caused by clostridium chauvoei

32
Q

Describe the process of Blackleg Gas gangrene ad how it reaches bacterial proliferation/toxin production

A

● Bacteria not introduced with a penetrating wound
● Spores spread haematogenously from the intestine & lodge into muscles (and remain latent) until local tissue trauma with hypoxia occur—> anaerobic conditions—>spores germinate—> bacterial proliferation
& toxins production/release

33
Q

Fat necrosis

A

Enzymatic- release of activated pancreatic lipases—>destruction of pancreatic adipose tissue
Traumatic- commonly caused by trauma; crushed fat
Idiopathic- abdominal fat necrosis of cattle

34
Q

3 Consequences of necrosis

A

● Inflammatory reaction within viable tissue – band of white blood cells
– hyperaemia
● Digestion and liquefaction of necrotic tissue – Phagocytosis (removal) by macrophages
– drainage through blood/lymphatic vessels
● Regeneration of normal tissue or fibrous scarring

Module 4 Week 1 (5 decks)

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