0.1 Cellular Response to Injury

Question 1

According to Claude Bernard, all living systems are homeostatic. How does injury impact this state?

Answer 1

Injury = moves away from homeostatic position

Response = method to achieve new homeostatic position

Response failure = death

Question 2

Cell / Tissue injury can be reversible or irreversible. What does this mean in terms of healing ability?

Answer 2

Reversible = can return to health after adaptation

Irreversible = inability to adapt causes cell dysfunction and death (can STILL heal, but harder + not fully)

Question 3

How is necrosis different from apoptosis?

Answer 3

Necrosis = Passive, aciidental cell death from inflammation

Apoptosis = Active, programmed cell dismantling, not inflammatory

Question 4

Reversible cell injury takes shape in 7 different ways. What are they?

Answer 4

1. Hydropic change (cellular swelling)
2. Fatty change (accumulation of lipids)
3. Hypertrophy (increased size)
4. Atrophy (decreased size/number)
5. Hyperplasia (increased number/proliferation)
6. Metaplasia (change in state)
7. Anaplasia (cancerous transformation)

Question 5

Atrophy can take two different forms, what are they?

Answer 5

Apoptosis = reduction in NUMBER of cells

Autophagy (self-eating) = reduction in SIZE of cells

Question 6

What are some pathological characteristics of hydropic change?

Answer 6

Swelling of ER, vacuoles, and mitochondria

Plasma membrane blebs

Loss of microvilli (fingerlike membrane protrusions)

Question 7

What are the pathological changes of fatty change?

Answer 7

Cells unable to metabolise lipids = accumulates in cytoplasm

Most apparent in tissues with high lipid metabolism eg liver

Question 8

COPD and Sialosis (persistent enlargement of major salivary glands) are examples of what type of reversible cellular injury?

Answer 8

Hypertrophy = swelling

Question 9

Chronic bacterial sialdenitis (salivary gland infection) is an example of what type of reversible cellular injury?

Answer 9

Atrophy = decreased size / number of cells

Question 10

What is the process behind autophagy?

Answer 10

1. Primary lysome unable to complete phagocytosis (lacking nutrients) becomes autophagic vacuole
2. Residual body of vacuole unable to undergo exocytosis like a normal phagolysome
3. Lipofuscion pigment granule lingers as brown/black granules in tissue

Question 11

In what situation is autophagy commonly found?

Answer 11

In muscles that have been worked too hard

Question 12

Traumatic keratosis is the proliferation of epithelial cells to form superficial swelling. What type of reversible injury is this an example of?

Answer 12

Hyperplasia = change in tissue by cell proliferation

Question 13

Metaplasia is more complex than hyperplasia. Why is that?

Answer 13

Metaplasia is the change in form from one to another

Hyperplasia is simply a change in size

Question 14

What is a common occurrence of metaplasia and why does it appear as a protective reaction?

Answer 14

Squamous metaplasia of respiratory epithelium in smokers

Makes the epithelium tougher and more resistant to smoke

Question 15

What is dysplasia?

Answer 15

Disordered growth = alteration in size, shape, and oragnisation

Necessary stage in cancerous transformation

Question 16

What is anaplasia?

Answer 16

Cancerous growth via loss of cell differentiation

Question 17

What is the key difference between metaplasia and dysplasia?

Answer 17

Metaplasia = REPLACEMENT of one cell by another

Dysplasia = gradual CONVERSION of one cell into another

Question 18

All froms of necrosis lead to cellular leakage and inflammation. What are these 4 types of necrosis?

Answer 18

1. Coagulative
2. Liquefactive
3. Caseous
4. Fat necrosis

Question 19

Coagulative necrosis involves the modification of the nucleus. What are the 3 key examples of this?

Answer 19

1. Pyknosis (dense)
2. Karyorrhexis (blebbing)
3. Karyolysis (destroyed)

Question 20

What is fat necrosis specific to?

Answer 20

Adipocytes

Often found in pancreas and breasts

Question 21

What physiological processes normally involve apoptosis?

Answer 21

Fusion of palate

Lumen formation in glands

Involution of breast (post-lactational or lobular/ageing)

Question 22

What are 5 commmon pathological examples of apoptosis?

Answer 22

1. Removal of excess cells in healing
2. Excessive apoptosis in diabetic healing
3. Endothelial injury in athersclerosis
4. Autoimmune destruction of cells
5. Response to some injuries eg radiation, radicals, viral infection

Question 23

What is the progression of necrosis?

Answer 23

1. Normal cell
2. Reversible injury occurs leading to swelling of ER and mitochondria + membrane blebbing
3. If no recovery, it beocmes a progressive injury
4. Breakdown of plasma membrane, organelles, and nucleus as well as leakage of contents causing inflammation

Question 24

What are the 5 key differences in cell structure between necrotic and apoptotic cells?

Answer 24

1. Size (necrotic = enlarged, apoptotic = reduced)
2. Nucleus (necrotic = modified, apoptotic = fragmented)
3. Plasma membrane (necrotic = disrupted, apoptotic = intact, but altered)
4. Cellular contents (necrotic = enzymatic digestion + leakage, apoptotic = intact)
5. Inflammation (necrotic = frequent, apoptotic = never)

Question 25

What are the 4 pathways towards morphology of cellular injury?

Answer 25

1. ATP depletion
2. Loss of membrane integrity / membrane damage
3. Increased Ca2+
4. Reactive oxygen species (ROS)