Cell Injury & Cell Death

Question 1

How do myocytes in the heart adapt to an increased load?

Answer 1

Hypertrophy

They get larger allowing them to pump more blood around the body to allow cells to receive the same amount of oxygen

Question 2

What happens to myocytes in the cells if there is a second injury to the heart?

Answer 2

It leads to cell injury

If this is not treated, it leads to irreversible cell death

Question 3

What is meant by hypertrophy and atrophy?

Answer 3

hypertrophy - increase in size of cells

atrophy - shrinkage of cells

Question 4

What is necrosis?

Answer 4

severe cell swelling and rupture

Question 5

What is apoptosis?

Answer 5

internally controlled cell death

Question 6

What is oncosis?

Answer 6

the series of cellular reactions following injury that precede cell death

Question 7

What are the major 7 causes of cell injury?

Answer 7

1. hypoxia
2. physical agents
3. chemical agents
4. immunological reactions
5. infectious agents
6. genetic derangements
7. nutritional imbalances

Question 8

How does trauma cause cellular injury?

Answer 8

through mechanical disruption of tissue

Question 9

How does carbon monoxide inhalation cause cellular injury?

Answer 9

it prevents oxygen transport around the body as carbon monoxide has a higher affinity for haemoglobin

Question 10

How does contact with strong acid cause cellular injury?

Answer 10

It coagulates tissue protein

Question 11

How does paracetamol overdose cause cellular injury?

Answer 11

metabolites bind to liver cell protein and lipoproteins

Question 12

How do bacterial infections cause cellular injury?

Answer 12

they release toxins and enzymes that cause cellular injury

Question 13

How does ionising radiation cause cellular injury?

Answer 13

it damages the DNA

Question 14

What are the 5 general biochemical mechanisms behind cellular injury?

Answer 14

1. ATP depletions
2. oxygen and oxygen derived free radicals can damage tissues
3. loss of intercellular calcium hemostasis
4. defects in membrane permeability
5. irreversible mitochondrial damage

Question 15

What are the 2 types of cell injury?

Answer 15

1. reversible

2. irreversible

Question 16

What 3 features characterise reversible cell injury?

Answer 16

1. decreased generation of ATP
2. loss of cell membrane integrity
3. defects in protein synthesis and DNA damage

Question 17

What further 3 features lead to irreversible cell injury?

Answer 17

1. severe mitochondrial changes
2. extensive damage to plasma membrane
3. swelling of lysosomes

Question 18

How does cellular swelling occur in reversible cell injury?

Answer 18

1. depletion of ATP leads to decreased activity of the Na/K pump
2. this leads to more Na being in the cell
3. Water moves into the cell by osmosis
4. this leads to cellular swelling

Question 19

In irreversible cellular injury, what happens when there is membrane damage to the mitochondria?

Answer 19

1. this leads to cytochrome c leakage
2. this activates caspaces
3. this triggers apoptosis

Question 20

In irreversible cellular injury, what happens when there is damage to the cell membrane?

Answer 20

1. this allows calcium to enter the cell
2. calcium activates proteases and enzymes, leading to enzymatic degradation of the cell
3. increased calcium also activates caspaces, which trigger apoptosis

Question 21

In irreversible cellular injury, what happens when there is damage to the lysosome membrane?

Answer 21

1. this leads to leakage of lysosomal enzymes into the cytosol
2. this leads to enzymatic degradation of the cell

Question 22

How many cells are affected in apoptosis?

Answer 22

It can involve just a single cell

Question 23

What happens if there is increased apoptosis?

Answer 23

it results in excessive cell loss e.g. atrophy

Question 24

What are the stages of apoptosis?

Answer 24

1. chromatin condenses and the membrane blebs
2. this is followed by cellular fragmentation as apoptotic bodies form
3. there is phagocytosis of apoptotic cells and fragments

Question 25

What is the inflammatory response like in apoptosis and necrosis?

Answer 25

necrosis involves an inflammatory response

apoptosis has NO inflammatory response

Question 26

What happens to cellular contents in necrosis?

Answer 26

they leak into the surroundings and can damage adjacent cells

Question 27

What is the difference in the size of the areas affected by apoptosis and necrosis?

Answer 27

apoptosis can affect just a single cell

necrosis affects large areas of tissue

Question 28

What are the 6 types of necrosis?

Answer 28

1. coagulative
2. liquefactive
3. gangrenous
4. caseous
5. fat necrosis
6. fibrinoid necrosis

Question 29

What is the commonest form of necrosis?

Answer 29

coagulative necrosis

Question 30

What happens to cells in coagulative necrosis?

Answer 30

the architecture of the cell is preserved

there is loss of proteins and enzymes

there is no proteolysis

Question 31

What is coagulative necrosis?

Answer 31

Coagulative necrosis is a type of accidental cell death typically caused by ischaemia or infarction

Question 32

What is liquefactive necrosis?

Answer 32

a type of necrosis which results in a transformation of the tissue into a liquid viscous mass

Question 33

What is gangrenous necrosis?

Answer 33

death of tissue due to lack of blood flow

it appears black

Question 34

What are the 3 types of gangrene?

Answer 34

wet, dry or gas

Question 35

What is caseous necrosis and what does it look like?

Answer 35

it is structureless dead tissue

it is amorphous pink material with necrotic debris in the centre

Question 36

What usually causes fat necrosis?

Answer 36

enzymes or trauma

Question 37

In what 2 conditions is fibrinoid necrosis seen?

Answer 37

1. malignant hypertension

2. autoimmune diseases