1 Cell Injury Flashcards
How do cells react to severe changes in environmental conditions?
Cell adaptation
Cell injury
Cell death
Define ‘disease’
A consequence of failed homeostasis with consequent morphological and functional disturbances to cells.
What determines the degree of an injury?
Type of injury
Severity of injury
Type of tissue affected
Define ‘cell injury’
Irreversible change within a cell
Name 3 causes of cell injury and cell death
Hypoxia Trauma Toxins Radiation Dietary deficiencies Micro-organisms Immune mechanisms
Define ‘ischaemia’
Loss of blood supply to a tissue
Define ‘hypoxia’
Oxygen deprivation to tissues
What is ‘hypoxaemic hypoxia’?
Arterial content of oxygen is low
What is ‘anaemic hypoxia’?
Decreased ability of haemoglobin to carry blood
What is ‘ischaemic hypoxia’?
An interruption of blood supply
What is ‘histiocytic hypoxia’?
Disabled oxidative phosphorylation enzymes so oxygen cannot be utilised.
Give 3 examples of toxins
Alcohol Poison Illegal Drugs Asbestos Pollutants Medicines
What is a ‘hypersensitivity reaction’?
The host tissue is injured after an overly vigorous immune reaction
What is an ‘immune reaction’?
The immune system fails to distinguish between self and non-self
What are the principle targets for cell damage?
Cell membranes
Nucleus
Proteins
Mitochondria
List the 4 effects of a high intracellular Ca2+ concentration
Decreased ATP
Decreased phospholipids
Disruption of protein production
Nuclear chromatin damage
What is a ‘free-radical’?
A very reactive molecule with a single unpaired electron in the outer orbit.
How are free-radicals produced in the body? When are they excessively produced?
Side products of the electron transport chain.
After chemical and radiation injury
How are free-radicals/reactive oxygen species (ROS) neutralised?
Antioxidants eg. H2O2
What is ‘ischaemia-reperfusion injury’?
Blood flow returns to a damaged tissue and is reoxygenised causing the production of more ROSs. This makes the damage worse.
What is the function of ‘heat-shock’ proteins?
Mend misfolded proteins and maintain cell viability.
What is ‘oncosis’?
Cell death with swelling (including the spectrum of changes that occur in injured cells prior to death)
Name some cellular symptoms associated with reversible injury
Blebs Swelling Clumping of chromatin Mitochondrial swelling ER swelling Dispersion of ribosomes
Name some features associated with irreversible injury.
Rupture of lysosomes and autolysis Defects in the cell membrane Lysis of ER Nuclear damage Myelin figures
Describe what is seen in:
i. ) Pyknosis
ii. ) Karyorrhexis
iii. ) Karyolysis
i. ) Accumulation of denatured proteins
ii. ) Fragmented nucleus
iii. ) No nucleus
What is ‘necrosis’?
The morphological changes that occur after a cell has been dead some time. The cell contents leak out and inflammation can be seen.
Name the 4 types of necrosis
Coagulative
Liquefactive
Caseous
Fat necrosis
What happens in ‘coagulative necrosis’?
The denaturing of proteins dominates over the release of active proteases.
The cellular architecture is preserved as a ‘ghost outline’
What happens in ‘liquefactive necrosis’? Where is it found?
Enzyme degradation is greater than denaturation so the tissues are enzymatically degraded. Found in the brain
What can be seen in caseous necrosis? What cause is it associated with?
Structureless debris
Infections, especially TB
What happens in fat necrosis? When does it occur?
Adipose tissue is destroyed by lipase release. It occurs after trauma.
What is gangrene? Name and describe the two types
Necrosis visible by the naked eye
Dry- modified by the air to become hard
Wet- modified by infection
What is an infarct? How are they caused?
An area of ishaemic necrosis
Clots in blood vessels, compression or twisting of the blood supply
When does a white infarct occur?
When there is an arterial deficiency. It only has one blood supply so is not reperfused.
When does a red infarct occur?
Venous insufficiency
Tissue is reperfused
Dual blood supply
When can a large potassium leak from a cell occur?
After a large amount of sudden cell death (eg. MI, burns, effective cancer treatment)
Why can enzyme leaks from cells be useful clinically? Give an example
Test plasma levels for released enzymes to diagnose problem
Example: troponin levels for MI, ALT/AST levels for liver damage
What is a side effect of a large myoglobin release?
Myoglobin blocks renal tubes causing dark urine
What is ‘apoptosis’?
Programmed cell death with shrinkage
How is apoptosis induced?
Enzymes are activated that degrade its own nuclear DNA and proteins
How many cells are affected by apoptosis at a time?
1
What enzyme mediated apoptosis
p53
How are the fragments of the apoptitic cell removed?
Phagocytosis
Why do abnormal accumulations occur within a cell?
The cell cannot metabolise the accumulation
What is the effect of fluid accumulation?
Swelling
What is the effect of lipid accumulation around the liver?
Steatosis and an increased liver size
What accumulation does a Mallory’s highline-hepatocyte have?
Accumulation of keratin
What is ‘dystrophic calcification’?
Pathological calcification of areas of localised damaged tissue
What is ‘metastatic calcification’?
Pathological calcification effecting the whole body and destroying bone tissue
