Cell Injury Flashcards
What is reversible cell injury
- cells adapt to changes in the enviroment
- return to normal once stimulus removed
What is irreversible cell injury
- permanent
- cell death as a consequence
What causes cell injury
Disease
What are the main factors of cell stress
- dose intensity
- cell vulnerability
What determines whether cell injury is reversible or irreversible
- depends on type, duration, severity of injury
- AND susceptibility/adaptability of the cell
What is hypoxia
Decreased oxygen supply
Name some causes of cell injury
- hypoxia
- physical agents
- chemicals/drugs
- infections
- immunological reactions
- nutritional imbalance
- genetics
What can causes hypoxia
Anaemia, respiratory failure
During hypoxia what can cells do to release energy
Cells can release energy via anaerobic mechanisms
Wont last forever
What is ischaemia
Reduction of blood supply to tissue
This can be causes by a blockage of arterial supply or venous drainage
More rapid/severe damage than hypoxia no nutrients or oxygen transported
Anaerobic energy release will stop
What can mechanical trauma cause
Affects structure, cell membranes
What can extremes of temperature effect
Affects proteins, chemical reactoons
What can ionising radiations cause
DNA damage
What can electric shocks cause in cell injury
Burns
Give some examples of infectious agents
- bacteria
- fungi
- viruses
- parasites
- protons
Can all produce cell injury
Some chemicals can cause …
Osmotic disturbance in excess
Name some immunological reactions that can cause cell injury
- anaphylaxis
- autoimmune reactions
- causes damage as a result of inflammation
How can nutrition cause cell injury
Too little
- can cause rickets, scurvy
- generalised anorexia
Too much
- hypervitaminosis A/D
- obesity
Name some genetic defects that cause cell injury
- sickle cell anemia
- inborn error of metabolism
- cancer
- subtle variations that can cause cell injury
What happens to cells during reversible injury
- aerobic respiration/ATP synthesis effected
- plasma membrane integrity
- enzyme and structural protein synthesis
- DNA maintaineece
What is cloudy swelling
During reversible cell injury ion pumps effected - sodium ion pump when the function is effected sodium and water will move into the cell as a result the cytoplasm and cell organelles will swell up
What are the causes of fatty liver
- alcohol abuse
- diabetes
- obesity
Explain fatty change in response to cell injury
Accumulation of lipid vascuoles in cytoplasm caused by disruption of fatty acid metabolism so that triglycerides cannot be released from the cell especially in the liver
What is necrosis
- cell death
- usually due to pathology
- irreversible cell injury
- Intracellular protein desaturation and lysosomal digestion of the cell
- inflammatory response in surrounding tissue
- histological changes take a while to appear
What response occurs in the surrounding tissues in nercosis
Inflammation
What are some nuclear changes of nercrosis
Pykynosis = nucleus shrinks, darker staining
Karyorrhexis = nuclear fragments
Karyolysis= the blue staining DNA in nucleus is digested by endonucleases and the blue staining fades away
What is coagulatuev necrosis
- no proteolysis of the dead cell due to the denaturation of enzymes, architecture of tissues is preserved for some days
- no nucleus, eosinophilic cells
- cells digested by lysosomes of leukocytes
What is liquefactive necrosis (colliquative)
- digestion of dead tissues so tissue in liquid viscous state
- focal bacteria pr fungal infections
- pus
- CNS necrosis as a result of hypoxia often manifested as liquefactive nercrosis
What is Caseous necrosis
- white appearance
- Tuberculous infection
- formation of granuloma as a result of mass apoptosis surrpunded by inflammatory cells
What is fibrinoid necrosis
- special type of necrosis in blood vessels
- immune complexes are deposited in artery walls together with fibrin (clotting factor) that leaks out of the vessels
Name some effects of necrosis
- functional depends on organ/tissue
- inflammation
- release of cell contents activates inflammation
- cell remains phagocytosed
- necrotic area replaced by a scar
- if remains not removed calcium salts may be deposited in the area
Why may calcium salts be deposited in the remains of necrotic tissue
If all the remains of the cell are not removed
What is apoptosis
Programmed cell death
Requires energy
Does not cause inflammation
Gets rid of unwanted cells
What enzyme causes apoptosis
Capsases
Name some physiological roles of apoptosis
- deletion of cell populations during embryogenesis
- hormone change
- cell deletion in proliferating cells - epithelial cells
- deletion of inflammatory cells
- deletion of self reactive lymphocytes
What can too much apoptosis cause
Degenerative diseases
What can too little apoptosis cause
Cancer
What is gangrenous necrosis
Coagulative necrosis with superimposed bacterial infection - liquefactive nercosis
What is fat necrosis
Focal areas of fat destruction, fat cells may be liquefied by activate pancreatic enzymes (acute pancreatitis)
What are some pathological triggers of apoptosis
- Hypoxia/ischemia
- viral infection
- DNA damage - if unrepairable p5£ triggers apoptosis
- caspases are activated enzymes that trigger apoptosis
- cell contents are degraded by enzymes activated by the cell
What affects does apoptosis have on cells
- cell shrinkage
- fragmentation into nucleoside size fragments
- interact, altered structure especially orientation of lipids
- interact- may be released in apoptic bodes
- no adjacent inflammation
- often physiologic
What is atherosclerosis
Accumulation of cholesterol in macrophages and smooth muscle cells in blood vessel walls
What are the macrophages called that accumulate around cholestrol
Foam cells
What is amyloid
Amyloid is a fibrillar protein material that is deposited as a result of pathologic processes leading to increased production of these proteins
Deposited in extracellular location (mostly on basement membrane) in various tissues and organs
What are the types of Amyloid
AL (amyloid light chain)
AA (amyloid associated)
Abeta
What is AL
Amyloid light chain, derived from light chain immunoglobulins from plasma cells
what is AA
Amyloid associated - derived from proteins synthesised in the liver
What is A beta
Amyloid beta causes Alzheimer’s disease
What is the stimuli for Alzheimer’s disease
Chronic inflammation, multiple myeloma, ageing, drug abuse
What is exogenous pathological pigmentation
- carbon deposition-commonest
- in macrophages in alveoli of lungs
- black pigment = anthracosis
- inhaled soot/smoke
- in coal workers
- tattoos
- heavy metal salts
- pigmentation associated with intravascular drug use
What is pathologic calcification
- dystrophic - deposits of calcium in necrotic tissue
- metastatic - deposits of calcium salts in normal, vital tissue with raised serum calcium levels, often seen in connective tissue of blood vessels, can compromise function of tissue
What are some causes of raised serum calcium
1) increased level of PTH (hyperparathyroidism) parathyroid gland tumour
2) destruction of bone tissue - leukaemia, metastasis to bone, immobilisation
3) excess vitamin D
4) renal failure