Cell injury Flashcards
What is meant by reversible cell injury?
Cells adapt to changes in environment and return to normal once stimulus is removed
What is meant by irreversible cell injury?
Permanent and cell death as a consequence
What can cause cell stress?
Intensity of stimuli
Cell vulnerability
What does the intensity of injury depend on?
Type of injury, duration and severity
Adaptability of the cell, nutritional status, metabolic needs
What are some causes of cell injury?
Hypoxia
Physical agents
Chemicals/drugs
Pathogens
Immunological reactions
Nutritional imbalance
Genetic defects
What is hypoxia?
Deficiency of oxygen
What are causes of hypoxia?
Anaemia, respiratory failure
How do hypoxic cells release energy?
Anaerobic mechanisms (glycolysis)
What is Ischaemia?
Reduction in blood supply to tissue
What are causes of ischaemia?
Blockage of arterial supply or venous drainage
What does ischaemia result in?
Depletion of oxygen and nutrients
Why is ischaemia more severe than hypoxia?
As anaerobic respiration will stop too
What does mechanical trauma effect?
Effects cell structure and membrane
What does extreme temperature effect?
Effects proteins and chemical reactions
What are different infectious agents which cause cell injury?
Bacteria
Viruses
Fungi
Parasites
Protons
What does an excess of glucose cause?
Osmotic disturbance
What’s an example of a occupational hazard?
Asbestos
What are examples of immunological reactions that cause cell injury?
Anaphylaxis
Auto-immune reactions
What is an example of nutritional imbalance?
Too little - Scurvy, Rickets
Too much- Hypervitaminosis A/D
What is scurvy?
Disease caused by vitamin C deficiency
What are examples of genetic defects which cause cell injury?
Sickle cell anaemia
Inborn error of metabolism
What is cloudy swelling in cells caused by?
When the cells are incapable of maintaining ionic and fluid homeostasis
Failure of energy dependant ion pumps in cell membrane
What is fatty change in cells caused by?
Accumulation of lipid vacuoles in cytoplasm caused by disruption of fatty acid metabolism so that triglycerides cannot be released from the cell, especially in liver
What is the common cause of fatty change in the liver?
Alcohol
Obesity
Diabetes
What is necrosis?
Cell death due to some form of pathology
How are cell remains from necrosis removed?
Phagocytosis
What response occurs in surrounding tissues from necrosis?
Inflammatory response
What is pyknosis?
When the nucleus shrinks
What is karyorrhexis?
When the nucleus splits into fragments
What is karyolysis?
Nucleus is digested by endonucleases
What is a cytoplasmic change in necrotic cells?
Appears paler because swollen
More pink due to denaturation of cytoplasmic structural and enzyme proteins
What are different types of necrosis?
-coagulative necrosis
-Liquefactive necrosis
-Caseous necrosis
-Gangrenous necrosis
-Fat necrosis
-Fibrinoid necrosis
What is liquefactive necrosis?
When cells are broke down to liquid state (PUS)
Where is fibrinoid necrosis?
Necrosis seen in immune reactions in blood vessels
What are the effects of necrosis?
Inflammation
Cell remains are phagocytosis
Necrotic area replaced with a scar
What is apoptosis?
Genetically programmed cell death
What are differences between apoptosis and necrosis?
Necrosis causes inflammation and doesn’t require energy, apoptosis doesn’t cause inflammation and does require energy
What are pathological triggers of apoptosis?
Hypoxia and ischaemia
Viral infection (CD8+ contain enzymes that induce apoptosis)
DNA damage
What are caspases?
Activated enzymes which trigger apoptosis
What are physiological roles of apotosis?
Deletion of cell populations during embryogenesis
Cell deletion in proliferating cell populations to maintain numbers
Deletion of inflammatory cells after an inflammatory response
Deletion of self reactive T cells in thymus
What does apoptosis look like in a cell?
What can an accumulation of cholesterol in cells cause?
Atherosclerosis
What is amyloid?
A fibrillar protein material which is deposited as a result of pathologic processes leading to increased production of these proteins
What can amyloid be stimulated by?
Chronic inflammation
Multiple myeloma
Ageing
Drug abuse
What diseases can amyloid cause?
Alzheimer’s
What are examples of endogenous pigmentation?
Melanin
Bilirubin
What are examples of exogeneous pathological pigementation?
Carbon (inhaled soot/smoke)
Tattoos
Heavy metal salts (lead)
What is dystrophic calcification?
Deposits of calcium phosphate in necrotic tissue
What is metastatic calcification?
Deposits of calcium in normal, vital tissue
What are causes of hypercalcaemia?
-Increased level of PTH
-Destruction of bone tissue
-Excess vitamin D
-Renal failure
