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MoD > MoD > Flashcards

MoD Flashcards

1
Q

What are the main targets of cell injury?

A

membranes (cell and organelles), nucleus, proteins, mitochondria

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2
Q

What is ischaemic reperfusion injury?

A

When blood returns to an area previously exposed to ischaemia (but is not yet necrotic), the return of blood flow causes more damage to the cells there than if it had been left without blood supply.

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3
Q

What are the ideas as to what causes ischaemic reperfusion injury?

A

^production of oxygen free radicals, ^ number of neutrophils TF more inflammation and damage, arrival of complement triggers complement pathway/response

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4
Q

What are free radicals?

A

Species which have a single unpaired electron TF they are unstable

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5
Q

What are the three most important free radicals?

A

Hydroxyl, superoxide, hydrogen peroxide

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6
Q

What is the definition of oncosis?

A

Cell death with swelling. It

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7
Q

List the causes of cell injury

A 
Hypoxia
Physical agents
Chemical damage
Immune mechanisms
Genetics
Micro-organisms
Dietary insufficiency/excess
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8
Q

List the types/causes of hypoxia?

A

Anaemic, hypoxiaemic, ischaemic, histiocytic

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9
Q

What is the difference between hypoxia and ischaemia?

A

Hypoxia is simply a lack of oxygen from any cause, ischaemia is a lack of blood supply to an area

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10
Q

Which is more dangerous hypoxia or ischaemia? Why?

A

Ischaemia, because this also causes a lack of delivery of substrates such as glucose to an area.

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11
Q

What does the extent of cell injury depend on?

A

Type of tissue, type of injury, severity of injury

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12
Q

What happens in reversible hypoxia?

A

Less O2 means less ATP, ATP usually pumps Na+ out of cell TF it accumulates, water enters cell causing cell and organelles to swell. More anaerobic respiration occurs, lower pH, affects enzymes and chromatin, ribosomes detach from ER.

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13
Q

When are free radicals often produced?

A

Cellular aging, high oxygen conc, chemical/radiation injury, ischaemic reperfusion

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14
Q

What happens in irreversible hypoxia?

A

Ca2+ enters cell, very high levels (from outside and ER and mitochondria) are very metabolically active TF activate lots of enzymes.

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15
Q

Which enzymes do high [Ca2+] activate?

A

Activate phospholipases, proteases, endonucleases, ATPase.

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16
Q

What is the effect of the activated enzymes due to high [Ca2+]?

A

Drop in ATP levels, disrupt membrane and cytoskeleton, damage DNA. Once lysosomal membrane broken-> releases enzymes TF more damage

17
Q

How can hydroxyl radicals be produced?

A

Radiation causing lysis of H2O, Fenton reaction, Haber Weiss reaction

18
Q

What are the anti-oxidants?

A

Vitamins A,C,E and glutathione are free radical scavengers, enzymes and storage proteins

19
Q

List two anti-oxidant enzymes and what they do

A

SOD superoxide Dismutase= O2- –> H2O2

Catalase, peroxidase= H2O2–>O2 + H2O

20
Q

What do storage proteins do in their anti oxidant role?

A

Isolate transition metals which catalyse formation of free radicals eg Fe2+

21
Q

What do heat shock proteins do?

A

Recognise incorrectly folded proteins, try to repair them if not destroy them. Eg Ubiquitin

22
Q

What is pyknosis?

A

Shrinkage of nucleus

23
Q

What is karryohexis?

A

Fragmentation of nucleus

24
Q

What is karryolysis?

A

Dissolution of nucleus

25
Q

List the three signs of irreversible change to nucleus

A

Pyknosis, karryohexis, karryolysis

26
Q

What is a sign of reversible nuclear damage/change due to oncosis that shows up under light microscopy?

A

Chromatin becomes slightly clumped

27
Q

What cytoplasmic changes can be seen under LM when a cell is reversible damaged by oncosis?

A

Less pink staining due to increased amount of water due to decreased membrane integrity.

28
Q

What cytoplasmic changes can be seen under LM when a cell is irreversibly damaged by oncosis?

A

More pink staining due to presence of more proteins eg detachment of ribosomes

29
Q

What is necrosis?

A

The morphological changes that occur after a cell has been dead a while

30
Q

What is apoptosis?

A

Cell death with shrinkage. Induced by itself by degrading DNA and proteins “self-induced suicide”

31
Q

Under EM, what reversible changes can be seen due to oncosis?

A

Cellular swelling and blebbing, clumped chromatin, dissociation of ribosomes from ER.

32
Q

Why do ribosomes become detached from ER during oncosis?

A

atp is usually used to hold ribosome in place TF Lack of ATP means it isn’t held there so well

MoD (10 decks)

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