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ATS EMS MOD > Lecture 3 - Cell injury and death > Flashcards

Lecture 3 - Cell injury and death Flashcards

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1
Q

What are the two forms of irreversible cell injury? (2)

A
  1. necrosis

2. apoptosis

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2
Q

Why is the maintenance of cellular steady state important? (4)

A
  1. preservation of genetic integrity
  2. normal enzyme content
  3. intact membranes and transmembrane proteins
  4. adequate supply of substrates and oxygen
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3
Q

What is cell injury?

A
  • biochemical and or morphological changes

- that occur when the steady state is disrupted by adverse influences.

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4
Q

What is cellular adaptation?

A

cells adapting to stress

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5
Q

What does cellular adaptation involve? (3)

A
  1. increased cellular activity - hyperplasia and hypertrophy
  2. decreased cellular activity - atrophy
  3. change in cell morphology - metaplasia
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6
Q

What 2 things can cell injury be?

A
  1. reversible - mild and transient

2. irreversible - severe and progressive

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7
Q

What is the aetiology of cell injury? (6)

A
  1. oxygen availability
  2. physical trauma
  3. chemical agents
  4. infectious organisms
  5. irradiation
  6. others - immunology, lack of nutrients and vitamins, genetics and ageing
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8
Q

What does oxygen availability entail?

A

hypoxia and anoxia

these are caused by ischaemia

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9
Q

What does reperfusion generate?

A

free oxygen radicals - problematic

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10
Q

What does mechanical trauma entail?

A

disruption of cell structure

thrombosis leading to ischaemia

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11
Q

What does physical trauma split into?

A
  1. mechanical

2. extremes of temperature

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12
Q

What is entailed in irradiation?

A

X ray and radioactive particles and the generation of free radicals causing damage to macromolecules

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13
Q

Which organs have a very high sensitivity to free radicals? (3)

A
  1. bone marrow
  2. gonads
  3. intestines
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14
Q

Which organs have a very low sensitivity to free radicals? (3)

A
  1. uterus
  2. pancreas
  3. adrenal
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15
Q

How is mitochondria function disrupted?

A
  1. disruption of oxidative phosphorylation
  2. hence less ATP
  3. hence less sodium pump action - active transport which requires ATP
  4. increased glycolysis
  5. other effects
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16
Q

What happens when the sodium pump in the mitochondria has decreased activity and what does this cause?

A
  1. increased influx of calcium ions, water and sodium ions
  2. increased efflux of potassium ions

Causes

  1. cellular swelling
  2. loss of microvilli
  3. blebs
  4. ER swelling
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17
Q

What are blebs?

A

rounded outgrowths on the surface of the cell due to ER swelling

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18
Q

What happens when there is increased glycolysis in the mitochondria?

A
  1. decreased glycogen

2. decreased pH - due to clumping of nuclear chromatin

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19
Q

What are the other effects of mitochondria damage?

A
  1. detachment of ribosome
  2. decreased protein synthesis
  3. causing lipid deposition
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20
Q

What is characteristic of sublethal cell injury?

A
  1. cell (cloudy) swelling
  2. fatty change

example - cirrhotic liver/ fatty liver

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21
Q

Is a sublethal injury enough to cause cell death?

A

no

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22
Q

What are the mechanisms of cell injury? (2)

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A
  1. free radical toxicity

2. membrane defects

23
Q

How do you detoxify free radicals?

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A

superoxide dismutase and antioxidants (vitamin A, C and E)

24
Q

Why do neutrophils and macrophages depend on superoxide dismutase?

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A

in order to kill bacteria

25
In membrane defects causing cell injuries what effect does this have on membrane gradient?
breakdown in metabolic gradient
26
What does the increase in calcium in membrane defects in cell injuries cause?
activation of a number of enzymes with harmful effects 1. ATPases - ATP depletion 2. Phospholipases - membrane damage 3. Proteases - break down membrane and cytoskeltal proteins 4. endonucleases - dna breakdown
27
What is cell death?
when steady state is unachievable after environmental insults
28
What is necrosis?
cell death as a result of lethal cell injury passive causes an inflammatory reaction
29
What do necrotic cells look like? (5)
1. coagulative - most common 2. caseous - cottage cheese 3. colliquative - brain 4. gangrene - wet and dry 5. fat and fibrinoid
30
What is characteristic of coagulative necrosis?
firm and slightly swollen
31
What is characteristic of colliquative necrosis?
total liquefaction and the site is marked with a cyst
32
What is characteristic of caseous necrosis?
TB surrounded by granulomatous inflammation
33
What is gangrenous necrosis?
wet gangrene - bowel infarct dry gangrene - diabetes
34
What is apoptosis?
programmed cell death active process
35
What are examples physiological apoptosis?
1. embryogenesis 2. involution 3. elimination of self reacting lymphocytes
36
What are examples of pathological apoptosis? (4)
1. dna/ protein damage 2. viral infections 3. cell killing by cytotoxic T cells 4. chemo/radiotherapy
37
What does the mechanism of apoptosis entail?
intrinsic and extrinsic pathways
38
What is P53 involved in and what can too much sun hence dan damage cause?
involved in dna damage detection cancer
39
In terms of extrinsic apoptosis what does BCL-2 a growth molecule inhibit?
cytochrome C hence inhibits apoptosis
40
What are the number of cells like in necrosis?
multiple
41
What is the cell size like in necrosis?
enlarged
42
What happens to the nucleus in necrosis?
1. pyknosis - irreversible condensation of chromatin in the nucleus of a cell undergoing apoptosis or necrosis 2. karyorrhexis - fragmentation of the nucleus 3. karyolysis - dissolution of a cell nucleus during mitosis
43
What are the cellular contents in necrosis?
enzymatic digestion - may leak out of cell
44
How frequent is adjacent inflammation like in necrosis?
frequent
45
Is necrosis pathologic or physiologic?
pathologic - irreversible cell injury
46
What are the number of cells like in apoptosis?
single
47
What is the cell size like in apoptosis?
reduced
48
What happens to the nucleus in apoptossis?
Fragmentation to apoptotic bodies
49
What happens to the plasma membrane in apoptosis?
it is intact
50
What happens to the plasma membrane in necrosis?
it is disrupted
51
What happens to the cellular contents in apoptosis?
intact
52
Is there any adjacent inflammation in apoptosis?
no
53
Does apoptosis have a physiological or pathological role?
physiological - means of eliminating unwanted cells

ATS EMS MOD (4 decks)

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