MoD Flashcards
What are the main targets of cell injury?
membranes (cell and organelles), nucleus, proteins, mitochondria
What is ischaemic reperfusion injury?
When blood returns to an area previously exposed to ischaemia (but is not yet necrotic), the return of blood flow causes more damage to the cells there than if it had been left without blood supply.
What are the ideas as to what causes ischaemic reperfusion injury?
^production of oxygen free radicals, ^ number of neutrophils TF more inflammation and damage, arrival of complement triggers complement pathway/response
What are free radicals?
Species which have a single unpaired electron TF they are unstable
What are the three most important free radicals?
Hydroxyl, superoxide, hydrogen peroxide
What is the definition of oncosis?
Cell death with swelling. It
List the causes of cell injury
Hypoxia Physical agents Chemical damage Immune mechanisms Genetics Micro-organisms Dietary insufficiency/excess
List the types/causes of hypoxia?
Anaemic, hypoxiaemic, ischaemic, histiocytic
What is the difference between hypoxia and ischaemia?
Hypoxia is simply a lack of oxygen from any cause, ischaemia is a lack of blood supply to an area
Which is more dangerous hypoxia or ischaemia? Why?
Ischaemia, because this also causes a lack of delivery of substrates such as glucose to an area.
What does the extent of cell injury depend on?
Type of tissue, type of injury, severity of injury
What happens in reversible hypoxia?
Less O2 means less ATP, ATP usually pumps Na+ out of cell TF it accumulates, water enters cell causing cell and organelles to swell. More anaerobic respiration occurs, lower pH, affects enzymes and chromatin, ribosomes detach from ER.
When are free radicals often produced?
Cellular aging, high oxygen conc, chemical/radiation injury, ischaemic reperfusion
What happens in irreversible hypoxia?
Ca2+ enters cell, very high levels (from outside and ER and mitochondria) are very metabolically active TF activate lots of enzymes.
Which enzymes do high [Ca2+] activate?
Activate phospholipases, proteases, endonucleases, ATPase.
What is the effect of the activated enzymes due to high [Ca2+]?
Drop in ATP levels, disrupt membrane and cytoskeleton, damage DNA. Once lysosomal membrane broken-> releases enzymes TF more damage
How can hydroxyl radicals be produced?
Radiation causing lysis of H2O, Fenton reaction, Haber Weiss reaction
What are the anti-oxidants?
Vitamins A,C,E and glutathione are free radical scavengers, enzymes and storage proteins
List two anti-oxidant enzymes and what they do
SOD superoxide Dismutase= O2- –> H2O2
Catalase, peroxidase= H2O2–>O2 + H2O
What do storage proteins do in their anti oxidant role?
Isolate transition metals which catalyse formation of free radicals eg Fe2+
What do heat shock proteins do?
Recognise incorrectly folded proteins, try to repair them if not destroy them. Eg Ubiquitin
What is pyknosis?
Shrinkage of nucleus
What is karryohexis?
Fragmentation of nucleus
What is karryolysis?
Dissolution of nucleus
