L1-3 Cell Injury and response

Question 1

What does cellular response depend on?

Answer 1

1. Type of injury
2. Duration of injury
3. Severity of injury

Question 2

What do the consequences of cell injury depend on?

Answer 2

1. Type of cell
2. State of cell
3. Adaptability of cell

E.g. under the same ischemic condition, striated muscles will be ok whereas neurons will die

Question 3

How does anoxia lead to cell damage?

Answer 3

Reduce level of ATP production, such that energy dependent sodium and calcium pump fails. This causes ionic imbalance –> cell swelling –> activation of lytic enzymes

Question 4

What is reperfusion damage?

Answer 4

Accelerated injury due to restoration of BF after a period of ischemia

Question 5

What is the speculated mechanism of reperfusion damage?

Answer 5

1. Exposure of compromised cells to a high level of calcium
2. Increased free radical production from compromised mitochondria and circulating inflammatory cells

Question 6

What are the possible causes of cellular ageing?

Answer 6

1. Reduced ability to repair damaged DNA
2. Defective protein homeostasis
3. Accumulation of cellular damage
4. Reduced cellular capacity to divide

Question 7

List the different types of necrosis

Answer 7

1. Coagulative necrosis (heart and kidney)
2. Liquefactive necrosis (brain)
3. Fat necrosis (pancreas)
4. Caseous necrosis (TB - lymph node)
5. Fibrinoid necrosis (blood vessel)

Question 8

What are the causes of apoptosis in pathological situations?

Answer 8

1. DNA damage
2. Accumulation of misfolded proteins
3. Infections (mainly viral)
4. Duct obstruction (atrophy in parenchymal organs)

Question 9

What are the 2 activities of caspases?

Answer 9

1. Activate caspase-activated DNAses
2. Degrade components of nuclear matrix and cytoskeletons

Question 10

What are the key players of extrinsic pathway of apoptosis?

Answer 10

1. TNF-alpha + receptor
2. Caspase 8
3. Caspase 3

Question 11

What are the key players of intrinsic pathway of apoptosis?

Answer 11

1. Intracellular sensor (BCL-2)
2. Cytochrome C from mitochondria
3. Caspase 9
4. Caspase 3

Question 12

Activity of caspase 3 and its consequences

Answer 12

Activate endonuclease –> breaking down of cytoskeleton and nuclear fragmentation

Question 13

How do apoptotic bodies make themselves known by phagocytes?

Answer 13

1. Movement of phosphatidyl Serene from the inside leaflet of cell membrane to the outside
2. Release of Annexin-1 protein, which binds to PS, acting as an “eat me” signal

Question 14

What are the examples of cells that undergo hypertrophy as a means of cellular adaptation?

Answer 14

Non-dividing cells such as:

1. Neurons
2. Skeletal muscles
3. Cardiac muscles

Question 15

Characteristics of cells undergoing apoptosis

Answer 15

1. Cell shrinks
2. Blebs form on the surface
3. Splitting up of cells to apoptotic bodies
4. Chromatin aggregation

Question 16

3 theories of metaplasia

Answer 16

1. Transdifferentiation of mature cell
2. Local stem cell differentiate under a different pathway
3. Circulating stem cell differentiate at a site different from site of origin