Cell Injury Flashcards
What is necrosis?
Severe cell swelling and rupture. Death of tissue following bioenergy failure and loss of plasma membrane integrity
Includes inflammation and repair
What is apoptosis?
Internally controlled cell death, Individual cell deletion in physiological growth control and in disease
Activated or prevented by many stimuli
Increased apoptosis results in excessive cell loss e.g, atrophy
What is oncosis?
Pre lethal changes preceding cell death
What can causes cell injury
Hypoxia, Physical agents, Temperature, trauma, radiation, Chemical agents, (Drugs etc), Immunologic reactions, Infectious agents, Genetic derangements, Nutritional imbalances
How can trauma cause cell injury?
Mechanical disruption of tissue
How can Carbon Monoxide inhalation cause cell injury?
Prevents oxygen transport
How can contact with strong acid cause cell injury?
Coagulates tissue protein
How can Paracetamol Overdose cause cell injury?
Metabolites bind to liver cell protein and lipoproteins
How can Bacterial infections cause cell injury?
Toxins and enzymes
How can ionising radiations cause cell injury?
Damage to DNA
General Biochemical Mechanisms of cell injury (5)
ATP depletions, Oxygen and oxygen derived free radicals, Loss of intercellular calcium homeostasis, Defects in membrane permeability, Irreversible mitochondrial damage
What is reversible cell injury?
Cell swelling, pallor, hydropic change, vacuolar degeneration
Decreased ATP = Decreased Na/K pump activity= Inc Na in cell= Inc water in cell (osmosis)= cellular swelling
loss of cell membrane integrity, defects in protein synthesis and DNA damage.
What is irreversible cell injury?
Mitochondrial swelling, lysosomes swells, damage to membrane, leakages of enzymes
Membrane damage to lysosomes= leakage of lysosomal enzymes into cytosol=enzymatic cell degradation
Membrane damage to cell membrane= Inc Ca in cell= activates caspaces =(apoptosis )/ activates proteases and other enzymes= enzymatic cell degradation
Membrane damage to mitochondria= Cyt C leakage= activates caspaces= apoptosis
What is Ischaemic/Reperfusion injury
cell injury?
New damage on reperfusion mediated by free oxygen radicals
Cellular swelling- necrosis/apoptosis
Necrosis
cellular shrinkage necrosis/apoptosis
Apoptosis
many cells affected -necrosis/apoptosis
Necrosis
once cell affected- necrosis/apoptosis
Apoptosis
cell content injected by macrophages necrosis/apoptosis
Necrosis
cell contents injected by neighbouring cells necrosis/apoptosis
Apoptosis
Inflammation -necrosis/apoptosis
Necrosis
No inflammation - necrosis/apoptosis
Apoptosis
Loss of membrane integrity- necrosis/apoptosis
Necrosis
Apoptotic body formation- necrosis/apoptosis
Apoptosis
Cell lysis- necrosis/apoptosis
Necrosis
Membrane blebbing but integrity maintained- necrosis/apoptosis
Apoptosis
Random degradation of DNA- necrosis/apoptosis
Necrosis
chromatin condensation and non-random DNA degradation- necrosis/apoptosis
Apoptosis
Mitochondria release pro-apoptotic proteins- necrosis/apoptosis
Apoptosis
Organelle swelling and lysosomal leakage- necrosis/apoptosis
Necrosis
Caspaces activation- necrosis/apoptosis
Apoptosis
What is autophagy?
Cell death: increased quantity of autophagosomes- allow recycling of cellular components, Atg-Autophagy related gene protein involved. No inflammatory response created.
What Is Coagulative Necrosis?
Commonest form, Occurs in most organs, Cells retain their outlines, Protein coagulate and no proteolysis occurs. Architecture preserved, loss of proteins and enzymes so metabolic activity ceases. Seen in Mi
What Is Liquefactive Necrosis?
Seen in brain, Due to lack of substantial supporting stroma, Neural tissue may totally liquify. Seen in Bacterial or fungal infection, CNS hypoxia
What Is Gangrenous Necrosis?
Putrefaction of the tissue, Cause is mostly infectious/ bacteria., Appear black. i.e. Limb ischaemia
Types: Wet gangrene, (associated with infection) Dry gangrene, Gas gangrene
What Is Fat Necrosis?
Causes: Enzymes,Trauma
Loss of architecture and lots of vacuoles are formed.
What Is Fibrinoid Necrosis?
Seen in Two conditions: Malignant hypertension (wall of artery are bright pick and with dark neutrophils) and Autoimmune diseases
What Is Caseous Necrosis?
Tuberculosis is main cause results in Structureless dead tissue, Amorphous pink material in centre with necrotic debris
What is the Commonest cause of medical admission in under 40s’?
Paracetamol/Acetaminophen overdose
48% of all poisoning /10,000 medical adms / year. It is the leading cause of acute liver failure.
Whats the size of the liver?
Largest organ in the body (1.2-1.5 kg
Whats the livers blood supply?
Dual blood supply from hepatic artery and portal vein –
Therefore much less susceptible to ischaemic injury than most organs
What are Idiosyncratic Hepatotoxins?
are rare and unpredictable drug reactions
What areIntrinsic hepatotoxins?
Drugs like Paracetamol in high doses cause liver injury in everyone
What are the major and minor routes of paracetamol metabolism?
Major safe pathways: Glucuronide/sulphate conjugation then renal excretion
Minor pathway: Via CYP2E1 and CYP1A2 = toxic metabolite NAQPI in safe doses this can conjugate then really be excreted so is safe however if toxic doses of paracetamol>4mg are taken then glutathione is depleted so NAPQI binds to cellular proteins= hepatic necrosisDrug metabolising enzymes are in liver cells
further away from portal tracts – they die by necrosis
therefore liver cells by the portal tract survive.