cell injury

Question 1

what is reversible cell injury?

Answer 1

cells adapt to changes in environment, return to normal once stimulus is removed

Question 2

what is irreversible cell injury?

Answer 2

permanent, cell death is a consequence

Question 3

what determines if an injury is reversible or not?

Answer 3

type,duration, severity of injury

susceptibility/adaptability of cell, nutritional status, metabolic needs

Question 4

give causes of cell injury

Answer 4

hypoxia
physical agents
chemicals/drugs
infections
immunological reactions
nutritional imbalance
genetic defects

Question 5

what is hypoxia?

Answer 5

deficiency of oxygen
causes:anemia/resp failure
disrupts oxidative resp processes- decreased ATP
cells can still release energy via anaerobic mechanisms

Question 6

what is ischaemia?

Answer 6

reduction in blood supply to tissue, caused by blockage of arterial supply or venous drainage, depletion of nutrients, more severe than hypoxia- anaerobic energy release stops

Question 7

describe physical agents

Answer 7

mechanical trauma- affects structure, cell membranes
extremets of temp affect proteins + chemical reactions
ionising radiation=DNA damage
electric shock=burn

Question 8

describe chemicals/drugs

Answer 8

simple chemicals in excess cause osmotic damage
poisons, environmental
occupational hazards cause inflammation
alcohol, smoking and recreational drug

Question 9

describe immunological reactions

Answer 9

anaphylaxis
auto-immune reactions
cause damage as a result of inflammation

Question 10

describe too little nutritional imbalance

Answer 10

scurvy, rickets, anorexia

Question 11

describe too much nutritional imbalance

Answer 11

hypervitaminosisA/D, obesity

Question 12

describe genetic defects

Answer 12

sickle cell anaemia
inborn error of metabolism
more subtle variations in genetic make up determine susceptibility to cell injury

Question 13

describe mechanisms of reversible injury

Answer 13

aerobic resp/ATP synthesis
plasma membrane integrity
enzyme and structural protein synthesis
DNA maintenance

Question 14

describe cloudy swelling

Answer 14

cells incapable of maintaining ionic and fluid homeostasis
failure of pumps in membrane
build up of intracellular metabolites

Question 15

describe fatty change

Answer 15

accumulation of lipid vacuoles in cytoplasm caused by disruption of fatty acid metabolism so that triglycerides cannot be released from cell esp. liver
occurs with toxic and hypoxic injury
macroscopically liver enlarged and pale

Question 16

what is necrosis?

Answer 16

cell death usually due to pathology
irreversible
protein denaturation and lysosomal digestion of cell
inflammatory response
phagocytosis

Question 17

what is pyknosis?

Answer 17

nucleus shrinks, darker staining

Question 18

what is karyorrhexis?

Answer 18

nucleus fragments

Question 19

what is karyolysis?

Answer 19

blue staining DNA in nucleus is digested by endonucleases- loss of blue = necrosis

Question 20

what are the cytoplasmic changes of necrosis?

Answer 20

appears paler, swollen, mose eosinophilic because of denaturation of cytoplasmic structural and enzyme proteins

Question 21

describe 1-coagulative necrosis

Answer 21

no proteolysis of dead cells due to denaturation of enymes
architecture of tissue preserved for days
no nucleus
cells digested by lysosomes of leukocytes
localised=infarct

Question 22

describe liquefactive necrosis

Answer 22

digestion of dead tissues so tissue in liquid viscous state
focal bacterial or fungal infections
necrotic material thick pale yellow in colour

Question 23

describe caseous necrosis

Answer 23

friable white appearance
mostly seen in TB infection
granuloma-fragmented cells and granular debris surrounded by inflammatory cells

Question 24

describe gangrenous necrosis

Answer 24

coagulative necrosis with superimposed bacterial infection- liquefactive

Question 25

describe fat necrosis

Answer 25

focal areas of fat destruction | fat cells may be liquefied by activated pancreatic enzymes

Question 26

describe fibrinoid necrosis

Answer 26

immune reactions in b.v | immune complexes are deposited in artery walls together with fibrin that leaks out of the vessels

Question 27

what are the effects of necrosis?

Answer 27

functional-depends on organ/tissue inflammation release of cell contents activates inflammation cell remains phagocytosed necrotic area replaced by scar if remains not removed calcium salts may be deposited

Question 28

what is apoptosis?

Answer 28

``` genetically programmed cell death orderly elimination of unwanted cells required E distinct pathways involved no inflammation ```

Question 29

what are 5 pathological triggers of apoptosis?

Answer 29

hypoxia/ischaemia viral infection DNA damage caspases activated by enzymes that trigger apop cell contents degraded by enzymes activated by cell

Question 30

what are the physiological roles of apoptosis?

Answer 30

deletion of cell populations during embryogenesis hormone change dependent involution cell deletion in proliferating cell populations to maintain constant no. cells deletion of inflammatory cells after an inflammatory response deletion of self reactive lymphocytes in thymus

Question 31

describe the morphology of apoptosis

Answer 31

``` cell shrinkage chromatin condensation membrane intact cytoplasmic blebs break off to form apoptotic bodies phagocytosed ```

Question 32

what can accumulate intracellularly?

Answer 32

excessive normal cellular constituent- water, lipid, glycogen abnormal endogenous/exogenous material- carbon, silica, metabolites, cholesterol

Question 33

describe cholesterol accumulation

Answer 33

atherosclerosis- in macrophages and smooth muscle cells in b.v walls found at sites of haemorrhage and necrosis

Question 34

what is amyloid?

Answer 34

fibrillar protein material deposited as a result of pathogic processes leading to increased prod. of these proteins, deposited in extracellular location in various tissues and organs

Question 35

what is pathological pigmentation?

Answer 35

build up of pigmented substances in cytoplasm | endogenous and exogenous

Question 36

what is endogenous pigmentation?

Answer 36

lipofuscin-cellular lipid breakdown products melanin haemosiderin-localised bruising bilirubin

Question 37

what is exogenous pathological pigmentation?

Answer 37

``` carbon deposition in macrophages in alveoli of lungs black pigment=anthracosis inhaled soot/smoke tattoos heavy metal salts ```

Question 38

describe dystophic pathologic calcification

Answer 38

deposits of calcium phosphate in necrotic tissue | serum ca normal

Question 39

describe metastatic pathologic calcification

Answer 39

deposits of calcium salts in normal vital tissue with raised serum ca levels often seen it ct of b.v can compromise function of tissue

Question 40

what are 4 causes of raised serum calcium?

Answer 40

increased PTH eg tumous destruction of bone tissue excess vit. D renal failure - causes secondary hyperparathyroidism