Cell injury

Question 1

What is meant by cell injury?

Answer 1

reversible
cells adapt to changes in environment
return to normal once stimulus removed
irreversible
permanent
cell death as consequence

Question 2

What does whether an injury is reversible or irreversible depend on?

Answer 2

on type, duration, severity of injury and on the susceptibility/ adaptivity of the cell

Question 3

What are some causes of cell injury?

Answer 3

hypoxia- decreased oxygen supply
physical agents (radiation)
chemicals/drugs
infections( bacterial toxins, viruses)
immunological agents
nutritional imbalance
genetic defects

Question 4

Describe hypoxia- what is it? Causes?

Answer 4

Deficiency of oxygen, disrupts oxidative respiratory processes in cell- decreased ATP, cells can still release energy via anaerobic mechanisms
causes anaemia, respiratory failure

Question 5

describe Ischaemia

Answer 5

reduction in blood supply to tissue
caused by blockage of aterial supply of venous drainage
more rapid/severe damage than hypoxia

Question 6

What are some physical agents that can cause cell injury?

Answer 6

mechanical trauma – affects structure, cell membranes
extremes of temperature – affect proteins, chemical reactions
ionising radiation – DNA damage
electric shock - burn

Question 7

What does chemical/ drug damage do to a cell?

Answer 7

disruption of cell membranes and proteins
simple chemicals (glucose), in excess cause osmotic disturbance
poisons (cyanide blocks oxidative phosphorylation), environmental (insecticides)
occupational hazards (asbestos) causes inflammation
alcohol, smoking and recreational drug

Question 8

what is an example of nutritional imbalance?

Answer 8

too little- scurvy, rickets
too much- hypervitaminosis A/D

Question 8

what is an example of nutritional imbalance?

Answer 8

too little- scurvy, rickets
too much- hypervitaminosis A/D

Question 9

What is an example of genetic defects affecting cell injury?

Answer 9

sickle cell anemia, cancer

Question 10

What happens to cells during reversible injury?

Answer 10

disruption to
aerobic respiration/ATP synthesis (mitochondrial damage)
plasma membrane integrity
enzyme and structural protein synthesis
DNA maintenance

Question 11

What in regards to morphology happens to the cell in reversible cell injury?

Answer 11

cloudy swelling
fatty change

Question 12

Describe cloudy swelling during cell injury

Answer 12

cells are incapable of maintaining ionic and fluid homeostasis
failure of energy dependent ion pumps in cell membrane loss of ATP/ energy, no build up of intracellular metabolites

Question 13

describe a “fatty change” during reversible cell injury

Answer 13

accumulation of lipid vacuoles in cytoplasm due to fatty acid metabolism released especially in liver
occurs with toxic and hypoxic injury- alcohol abuse, diabetes

Question 14

What is necrosis?

Answer 14

cell death- usually due to pathology and is IRREVERSIBLE
cell membrane is disrupted leading to leakage of cell contents- inflammatory response around tissue

Question 15

Describe the microscopical changes of necrosis?

Answer 15

pyknosis = nucleus shrinks; darker staining
karyorrhexis = nucleus fragments (K)
karyolysis = the blue staining DNA in nucleus is digested by endonucleases and the blue staining fades away (K)
end result is loss of the blue staining nucleus – a useful sign that a cell is necrotic

Question 16

What are the different types of necrosis?

Answer 16

1- coagulative necrosis-
2- liquefactive necrosis-digestion of dead tissues, tissues in liquid viscous state
3- caseous necrosis- usually seen in tuberculous infection
4/5- gangrenous and fat necrosis- bacteria and areas of fat destruction
fibrinoid necrosis

Question 17

describe fibrinoid necrosis

Answer 17

special type seen in immune reactions in blood vessels

Question 18

What are effects of necrosis?

Answer 18

functional depends on organ/ tissue
inflammation
release of cell contents activates inflammation
replaced by scar- undergoes repair
if remains are not removed then calcium salts may be depositeded in necrotic tissue

Question 19

What is apoptosis?

Answer 19

genetically programmed cell death
orderly elimination of unwanted cells
can occur in pathological situautions
Requires energy
does NOT cause inflammatory

Question 20

What are pathological triggers of apoptosis?

Answer 20

hypoxia/ ischemia
viral infection
DNA damage
caspases ACTIVATED ENZYMES that trigger apoptosis

Question 21

What are physiological roles of apoptosis?

Answer 21

deletion of cell populations during embrogenisis
hormone chnage depentent involution- uterus, breast, ovary
deletion of inflammatory cells after an inflammatory response
deletion of self reactive lymphocytes in the thymus

Question 22

What is the morphology of the cell during apoptosis?

Answer 22

cell shrinkage
chromatin condensation – packaging up of nucleus
cell membrane remains intact, with formation of cytoplasmic blebs
break off to form apoptotic bodies
phagocytosed, but no widespread inflammation
everything is contained in cell membrane

Question 23

compare necrosis with apoptosis

Answer 23

cell size- N- enlarged A- reduced
nuclues- N-pyknosis-karyorhexis-karyolysis A-fragmentation into nucleosome size fragments
plasma membrane N-disrupted A-intact may be released
Cellular contents N- leak out A- intact
inflammation- N- Frequent A-No
Pathogenic role N-invariably pathogenic A- often physiolgic- eliminated unwanted cells

Question 24

what is atherosclerosis?

Answer 24

accumulation of cholesterol in macrophages and smooth muscle cells in blood vessel walls

Question 25

What is amylois?

Answer 25

is a fibrillar protein material that is deposited as a result of pathologic processes leading to increased production of these proteins. 3 types AL-light chain immunoglobins, AA- synthesized in liver AB- alzheimers

Question 26

What is endogenous pigmentation?

Answer 26

lipofuscin- cellular lipid breakdown products
melanin
haemosiderin
Billirubin
all appear brown in slide
carbon deposisted commonest

Question 27

what is dystrophic?

Answer 27

deposits of calcium phosphate in necrotic tissue