2. Pathology - cellular response to injury (cell adaptations and sub cellular injury and cell death)

Question 1

What are some of the mechanisms of cellular adaptation upon encountering stress

Answer 1

Hyperplasia (increase in number)
Hypertrophy (increase in size)
Atrophy (shrinkage in cell size)
Metaplasia (replacement of one cell type)

Question 2

What are the stimuli triggering adaptations

Answer 2

physical
chemical
microbiological
hypoxia
inflammation 
immunological reactions (self antigen, anaphylaxis) 
genetic
nutritional imbalance 
aging

Question 3

How does reversible injury differ to adaptation

Answer 3

adaptation is where cells modify to cope with stress whereas reversible injury to cells causes morphological/structural and functional changes

e.g. cells may undergo hydropic, fatty, degenerative change
connective tissue can respond with inflammation, regeneration, repair, scarring and calcification

Question 4

irreversible injury results in cell _____ by one of two mechanisms, ________ or ___________

Answer 4

death, apoptosis, necrosis

Question 5

Describe the sub-cellular process in hypoxia

Answer 5

1. Lack of oxygen impairs aerobic respiration, the cell switches to anaerobic respiration
2. pH of the cytosol decreases, becomes more acidic
3. Mitochondria swells, loss of electron transport, formation of free radicals
4. Decrease ATP production, impaired ion channels and protein synthesis/folding
5. Calcium ions activating enzymes, lysing proteins
6. Nuclear DNA clumping
7. Cell membrane blebing, damage

Question 6

What are the microscopic featrues of irreversible injury

Answer 6

1. nuclear shrinkage or nuclear fragmentation
2. breakdown of cell membrane
3. aggregates (protein denaturing)
4. cytoplasmic vacuoles, leakage and enzymatic digestion of cellular contents
5. increased eosinophilia under the microscope

Question 7

which is lost first in cell injury, function or morphology

Answer 7

function is lost before morphology due to mitochondrial malfunction and cell membrane disturbance

Question 8

what can cause necrosis

Answer 8

hypoxia
infections
toxin
immunological injury
physical agents

Question 9

describe coagulative necrosis

Answer 9

• solid tissue
• often in infarcts
• swollen, firm, pale appearance
• tissue architecture retained
• intra-cellular architecture lost

Question 10

describe liquifactive necrosis

Answer 10

• autolysis of cells, release and activation of intracellular enzymes
• digestion of dead cells see after hypoxia to brain to infections

Question 11

describe caseous necrosis

Answer 11

• cheese like consistency
• dry crumbly
• associated specifically with TB due to properties of the bacteria and the immune response, can occur in any tissue
• complete loss of cell and tissue architecture

Question 12

Describe Gangrenous necrosis

Answer 12

• Putrefaction (foul-smelling and discoloration)

Question 13

describe gummatous necrosis

Answer 13

similar to coagulative, associated specifically with syphilis
- tissue are yellow and rubbery

Question 14

Describe fibrinoid or hyaline necrosis

Answer 14

• found in arteries and arterioles, associated with hypertension
• hyaline: glassy, amorphous and eosinophilic
• firbinoid: resembles fibrin, bright pink and amorphous

Question 15

describe reversible injury

Answer 15

a mild form of injury, the function and morphological changes are reversible if the damaging stimulus
is removed

Question 16

describe apoptosis

Answer 16

regulated and programmed cell death, nuclear dissolution
the cell activates own enzymes that degrade its DNA
the membrane remains intact, no leakage
fragments breaks off
engulfed by scavenger cells
no inflammation