Cell Injury Flashcards
With a severe change in environment what are the 3 main outcomes for cells?
- Cell adaption
- Cell injury
- Cell death
What is the definition of disease?
- Consequence of failed homeostasis with consequent morphological and functional disturbances
What does the degree of injury depend on?
- Type
- Severity
- Type of tissue
What is hypoxiaemic hypoxia?
- Arterial O2 content is low
- Reduced inspired PO2 at altitude
- Decreased absorption
What is anaemic hypoxia and what are the possible causes?
- Decreased ability of Hb to carry O2
- Anaemia
- Co poisoning
What is Ischaemia what are the possible causes and consequences?
- Interruption of blood supply
- Blockage of a vessel
- Heart failure
What is histiocytic hypoxia and the possible causes?
- Inability to utilise O2 in cells due to disabled oxidative phosphorylation enzymes
- Cyanide poisoning
Give examples of possible toxins to cells.
- Poisons
- Alcohol
- Increased concentration of O2
- Pollutants
- Medicines
What is a hypersensitivity reaction?
- Host’s tissues are injured due to an overly vigorous immune reaction
- e.g urticaria
What is autoimmune damage?
- When immune system fails to distinguish self from non-self
What are the biochemical results of ischaemia and why?
- Decreased ox. phosphorylation of mitochondria -> decreased ATP
- Decreased Na/K pump -> Increased Ca/Na/H2O, decreased K -> cellular swelling/loss of microvilli/ER swelling/myelin figures
- Increased glycolysis -> decreased pH/glycogen -> clumping of nuclear chromatin
- Detachment of ribosomes -> decreased protein syn. -> lipid deposition
What is the main free radical injury and what can this go on to do?
- Lipid peroxidation -> more free radicals -> autocatalytic chain reaction
- Attacks other proteins/carbs/DNA -> mutagenic
What are the cellular defences to free radicals?
- Enzymes
- Vit A/C/E are free radical scavengers
- Storage proteins
What is the link between ischaemia and free radical damage?
- Reperfusion injury: blood flow returned to damaged cell
- Increased O2 free radicals with re-oxygenation
Heart shock proteins are a defence against cell injury, what do they do?
- Mends misfolded proteins and maintains cell viability
- Via unfoldases/chaperones
What is oncosis?
- Process of cell death with swelling.
- Spectrum of changes that occurred in injured cells prior to death
What is necrosis?
- Morphological changes in a living organism
What is apoptosis?
- Shrinkage
- Induced by a regulated intracellular programme where a cell activates enzymes that degrades it’s own nuclear DNA and proteins
What is coagulative necrosis?
- Denaturation of proteins dominates over release of active proteases
- Ghost outline of cells
What is Liquefactive necrosis?
- Enzyme degradation’s substantially greater than denaturation
- Leads to enzymatic digestion (liquefaction) of tissues
What is caseous necrosis and what does it look like?
- Structureless debris
- Cheese
What are the causes of the following:
- Dry gangrene
- Wet gangrene
- Gas gangrene
- Dry: dehydrated necrosis
- Wet: liquefactive necrosis
- Gas: anaerobic bacteria
What is an infarction?
- Tissue death caused by obstruction of tissue’s blood supply
- Ischaemia necrosis
What is a white infarct?
- Solid tissue
- End arteries affected so no blood supply.
What is a red infarct?
- Haemorrhage
- Dual blood supply
- Obstruction of venous pressure builds up hence red colour.
What does the consequences of infarct depend on?
- Alternative blood supply
- Speed of ischaemia
- Tissues involved
- O2 content of blood.
During cell death potassium can leak from cells what effect can it have on the body?
- Toxic to the heart
- Can damage heart if damaged heart cells or massive necrosis
- Tumour lysis syndrome
How can enzymes be used for diagnosis?
- Enzymes with smallest molecular weight are released first so can be used to pinpoint the damage area.
How does physiological apoptosis work and what’s its use in embryonic development?
- Kills individual cells if infected
- Apoptotic cells are in inter-digital web space so need to break down otherwise -> webbed digits
- Helps to sculpt during embryonic development
What is pathological apoptosis?
- Destruction of cell due to faulty DNA
Draw a condensation, fragmentation cell and apoptotic bodies
- Condensation: very curvy
- Fragmentation: almost spikey
- Apoptotic bodies: droplets
What needs to be activated before apoptosis will occur?
- Capsases
What is intrinsic apoptosis?
- Mainly when DNA damage has occurred
- Mitochondria become more permeable
- Cytochrome C is released
- Caspases activated
What is extrinsic apoptosis?
- TRAIL and FAS ligands bind to ‘death receptors’ this activates caspases mediating apoptosis
Why may abnormal accumulations occur?
- Cell’s own metabolism
- Extracellular space e.g spilled blood
- Outer environment e.g dust
What are the 5 main groups of Intracellular accumulations?
- Water & electrolytes
- Lipids
- Carbohydrates
- Proteins
- Pigments
What happens in aspirin overdose?
- Arachidonic acid -> COX 1 -> Protective prostaglandins -> stomach mucosa / Platelet stickiness
- Arachidonic acid -> COX 2 -> Inflammatory prostaglandins -> pain/inflam/fever
