Cell Injury

Question 1

What is reversible cell injury?

Answer 1

Cells adapt to changes in environment - return to normal upon removal of stimuli

Question 2

What is Irreversible cell injury?

Answer 2

Permanent - cell death

Question 3

What are the causes of cell injury (=aetiology)?

Answer 3

Hypoxia
Ischaemia
Physical agents
Chemicals/drugs
Infections
Immunological reactions
Nutritional imbalance
Genetic defects

Question 4

What is Hypoxia?

Answer 4

O2 deficiency
Disrupting oxidative respiratory processes
Anaerobic mechanism engage

Question 5

What is Ischaemia?

Answer 5

Reduced blood supply
Caused by atherosclerosis
Hypoxia + Nutrient deficiency
More severe

Question 6

How physical agents may cause cell injury?

Answer 6

Mechanical trauma
Temperature
Ionising radiation- DNA damage
Electric shock-burn

Question 7

How chemical & drugs may cause cell injury?

Answer 7

Osmotic disturbance - excess glucose
Poisons - cyanide
Occupational hazards - asbestos
Alcohol, smoking, drug abus

Question 8

How immunological reaction may cause cell injury?

Answer 8

Anaphylaxis - tp1 HS
Auto-immune reactions (tp 2, antibodies directed towards host antigens, tp 3 – antigen-antibody complex)
Damage mediated by inflammation

Question 9

How Nutrition imbalance can cause cell injury?

Answer 9

Inadequate:
Specific- rickets, scurvy
Generalised- Anorexia

Excessive:
Specific - Hpervitaminosis
Generalised - Obesity

Question 10

How Genetic defects may cause cell injury?

Answer 10

Sickle cell anaemia
Inborn error of metabolism
Cancer

Question 11

Injury to cells causes disruption to:

Answer 11

• Aerobic respiration/ATP synthesis (Mitochondrial damage)
• Plasma membrane integrity
• Enzyme & structural protein synthesis
• DNA maintenance

Question 12

What happen when cells present as cloudy swelling?

Answer 12

• Cells incapable of maintaining ionic & fluid homeostasis
• ATP dependant pumps lose function → Influx of Na & H20
• Build up of intracellular metabolites

Question 13

What happen when cell present as fatty changes?

Answer 13

• Lipid vacuole accumulation → via fatty acid metabolism disruption
• Triglycerides cannot be released from cell
• Toxic & Hypoxic injury - Alcohol abuse, obesity, diabetes
• Commonly associated with enlarged liver & spleen

Question 14

What is necrosis?

Answer 14

Cell death (Usually from pathological consequences)

Question 15

What are the nuclear changes in necrosis?

Answer 15

• Pyknosis - Nucleus shrinks (Darker stain)
• Karyorrhexis - Nucleus fragments
• Karyolysis - Dissolution of Nuclear components

Question 16

What are the cytoplasmic changes in necrosis?

Answer 16

• Appears paler & swollen
• Sometime more eosinophilic → Increased denaturation of cytoplasmic enzymes /protein

Question 17

Mention types of necrosis?

Answer 17

Coagulative necrosis
Liquefactive necrosis
Caseous necrosis
Gangrenous necrosis
Fat necrosis
Fibrinoid necrosis

Question 18

What is infarct?

Answer 18

Localised area of coagulative necrosis

Question 19

What type of necrosis it appearance like cheese?

Answer 19

Caseous necrosis

Question 20

What type of necrosis seen in immune reactions in blood vessels?

Answer 20

Fibrinoid necrosis

Question 21

What type of necrosis is characterize by release of lipases, formation of fatty acids, saponification ?

Answer 21

Fat necrosis

Question 22

What are the effects of necrosis?

Answer 22

Loss of function - Organs/tissues
Inflammation - Phagocytosis and clearance of necrotic tissue
Scar tissue generation - Repair
Calcium salt deposition - If necrotic remains are still present

Question 23

What is Apoptosis?

Answer 23

Genetically programmed cell death

Question 24

What are the Apoptotic triggers?

Answer 24

Hypoxia/Ischaemia
Viral infection - mediated by CD8+ (Induced apoptosis)
DNA damage - mediated by p53 (Tumour-suppressor gene)
Caspases - active enzymes that trigger apoptosis

Question 25

What are the physiological functions/roles of apoptosis?

Answer 25

Embryogenesis - Cell population deletion Hormone mediated involution - Uterus, breast, ovary Population maintenance - epithelium Inflammatory cell deletion - once threat is resolved Negative selection of T cells - In thymus

Question 26

What too much and little apoptosis cause?

Answer 26

Too much apoptosis= degenerative diseases Too little apoptosis= cancer

Question 27

What is Intracellular accumulation?

Answer 27

- Excessive normal cellular constituents → Water, lipid, glycogen - Abnormal endogenous/exogenous material → Carbon, Silica, metabolites, cholesterol

Question 28

What is cholesterol accumulation?

Answer 28

- Atherosclerosis - build up in smooth muscle of blood vessel walls - Fatty necrosis - Presence of foam cells - Where macrophages ingest lipid

Question 29

What is Amyloid?

Answer 29

- Fibral protein deposition → due to increased pathological production - Deposited mostly on basement membranes of tissue/organs

Question 30

Mention types of Amyloid:

Answer 30

- AL amyloid - Amyloid light chain → From light chain immunoglobulins from plasma cells - AA amyloid - Amyloid associated → protein derived from liver - Aβ amyloid - Alzheimer’s disease

Question 31

Mention Amyloid Stimuli?

Answer 31

- Chronic inflammation - Multiple myeloma - Ageing - Drug abuse

Question 32

What is Pathological Pigmentation?

Answer 32

Pigmented substance build up in cytoplasm

Question 33

Mention Endogenous pigmentation

Answer 33

Melanin Bilirubin Hameosiderin-localised bruising Lipofuscin-cellular lipid breakdown products

Question 34

Mention Exogenous pigmentation

Answer 34

Carbon deposition Tattoos Heavy metal salts - Lead Intravascular drug use

Question 35

Pathological Calcification

Answer 35

Dystrophic calcification → Calcium phosphate deposits in necrotic tissues Metastatic calcification → deposits in vital tissue due to 📈 serum calcium

Question 36

What causes raised calcium levels?

Answer 36

- Increased PTH activity → Hyperparathyroidism - Bone tissue destruction → via bone metastasis (Leukaemia) - Vitamin D excess - Renal failure - secondary hyperparathyroidism