Lecture 1 - Cell Injury Flashcards
what are 8 methods of cell injury?
- hypoxia
- toxins
- heat
- cold
- trauma
- radiation
- microorganisms
- immune mechanisms
what is hypoxia?
reduced o2
what are the reversible changes in cell injury?
oxidative phosphorylation decreases
amount of atp decreases
increased amount of anaerobic glycolysis decreasing pH
low atp means Na accumulates in cell so cell swells
detachment of ribosomes lead to decrease in protein synthesis
what are the irreversible changes in cell injury?
huge accumulation of cytosolic Ca
several enzymes activated resulting in cell death
what are the reversible structural changes in cell injury?
swelling chromatin clumping autophagy ribosome dispersal blebs
what are the irreversible structural changes in cell injury?
nuclear changes
lysosomal rupture
membrane defects
endoplasmic reticulum lysis
define necrosis
changes that occur after cell death in living tissue
define apoptosis
programmed cell death
what are the two common types of necrosis?
coagulative
liquefactive
what are the two rarer types of necrosis?
caseous
fat
describe coagulative necrosis
more protein denaturation than enzyme release
cellular architecture somewhat preserved leaving ghost outline
tends to be due to infarcts
describe liquefactive necrosis
more enzyme release than protein denaturation
tissue is lysed and disappears
tends to be due to infection
describe caseous necrosis
tissue appears amorphous
halfway between coagulative and liquefactive
in lung is likely to be tb
describe fat necrosis
occurs when cell death is in adipose
what is gangrene?
grossly visible necrosis
what is wet gangrene?
liquefactive
infection –> neutrophils –> proteolytic enzymes
what is dry gangrene?
coagulative
eg umbilical cord after birth
what is an infarct?
necrosis due to ischaemia
what is a white infarct?
occlusion of an end artery, no peripheral blood vessels leaving the area entirely without blood
eg kidney
what is a red infarct?
occlusion of vessel leads to build up of blood which all haemorrhages at once, increased pressure decreases blood flow
eg bowel
What are the 4 types of hypoxia?
Hypoxaemic
Anaemic
Ischaemic
Histiocytic
What is hypoxaemic hypoxia?
Arterial content of oxygen is low
What is anaemic hypoxia?
Decreased ability of haemoglobin to carry oxygen
What is ischaemic hypoxia?
Interruption to blood supply
What is histiocytic hypoxia?
Inability to utilise oxygen
What are the 4 essential cell components?
Cell membranes, nucleus, proteins, mitochondria
What is ischaemia-reperfusion injury?
Blood flow is returned to a tissue that has been subject to ischaemia but hasn’t reached necrosis
What can cause ischaemia-reperfusion injury?
Increased production of oxygen free radicals with reoxygenation
Increased number of neutrophils on reestablishment of flow leads to more inflammation and damage
Delivery of complement proteins and activation of the complement pathway
What do free radicals do to lipids?
Cause lipid peroxidation
What causes heat shock?
Any injury, not just heat
What do heat shock proteins do?
Stay in the cell.
Important for protein repair (including refolding wrongly folded proteins).
What are the main 3 changes seen after cell injury under a light microscope?
Cytoplasmic changes
Nuclear changes
Abnormal intracellular accumulations
What cytoplasmic changes are seen under a light microscope?
Reduced pink staining due to water accumulation THEN increased pink staining due to ribosome detachment
What nuclear changes are seen under a light microscope?
Chromatin clumping
Pyknosis, karryohexis and karryolysis of the nucleus.
Define oncosis
Cell death with swelling
Define steatosis
Accumulation of triglycerides
