Cell injury Flashcards
Give some examples of causes of cellular injury
- Oxygen deprivation
- Physical agents e.g. burns, trauma, cold, radiation
- Viruses, bacteria, fungi
- Immunological reactions
- Nutritional imbalances
- Chemical agents and drugs
Name 4 intracellular systems that are most vulnerable to cellular injury
- Cell membranes
- Aerobic respiration (mitochondria)
- Protein synthesis
- Genetic apparatus
How is ischaemia linked to cellular injury?
When there is a reduction in blood there is a reduction in oxygen, meaning there is less ATP.
This means there is less energy to counteract the osmotic pressure.
Potassium and magnesium leave cells.
Water is pulled into the cell as sodium and calcium move in so the cell swells.
Which biochemical mechanisms can cause cell injury?
- ATP depletion
- Oxidative stress
- Loss of intracellular calcium homeostasis
- Defects in membrane permeability
- Mitochondrial damage
Describe the effects on a cell when there is a reversible ischaemic cell injury
- Cell swelling
- Reduced cellular pH
- Reduced protein synthesis
Why is the pH of a cell affected when there is an ischaemic injury?
- Cell relies on anaerobic glycolysis for energy production
- Depletion of glycogen stores
- Accumulation of lactic acid
- Reduced cellular pH
When do free radicals occur in a cell?
When the cell is damaged due to ischaemia and there is sudden replenishment of oxygen
Which enzymes are activated by increased cytosolic intracellular calcium?
- ATPase
- Phospholipase
- Endonuclease
- Protease
Describe the morphology of a reversible cell injury
Cell swelling
Decreased cell function
Some cell death at low levels
Give a definition of a free radical
Extremely unstable, highly reactive chemical species with a single unpaired electron in an outer orbital
Give 3 sources of free radicals
- Hydrolysis of water by ionising radiation
- Redox reactions e.g. respiration
- Metabolism of exogenous chemicals
Why can death of cells occur after blood flow resumes?
Reperfusion injury
- increased generation of oxygen free radicals during reoxygenation
- cytokines and adhesion molecules expressed by hypoxic cells leading to inflammation
