Cell Injury Flashcards
What is the main reason of cell death
Oxygen deprivation
Hypoxia
Ischemia
What is Hypoxia
Loss of blood supply from impeded blood flow or reduced venous drainage in a tissue
What is Ischemia
Compromises the availability of metabolic substrates including glucose, tends to injure tissues faster than hypoxia
Other causes of Cell injury
Physical agents: mechanical trauma, burns,cold
Chemical agents and drugs: glucose, salt, hypertonic concentration, poisons, environmental pollutants
Infectious agents
Immunologic reactions: endogenous self ag, autoimmune disease,reaction to foreign protein or drug.
Genetic rearrangements: genetic injury, chromosomal abnormality
Nutritional imbalance: anorexia nervosa, obesity, atherosclerosis.
The cellular response to injurious stimuli depends on
Type of injury
Duration
Severity
The consequences of cell injury depend on the
Type
State
Adaptability of the injured cell
Which essential cellular components with an abnormality results with cell injury
Aerobic respiration involving mito oxidative phosphorilation and production of ATP
Maintenance of the integrity of cell membranes
Protein synthesis
Preservation of the integrity of the genetic apparatus of the cell
Which structure is responsible for turning injury reversible to irreversible
Integrity of cell membranes
Effects of degradation in ATP to Na pump
Na pump activity decreases— Ca+, H20 and Na+ influx and K+ efflux increases— ER swelling, Cellular swelling, Loss of microvilli, BLEBS
Effects of ATP decrease to Anaerobic glycolysis
Anaerobic glycolysis increases— glycogen and pH decreases — clumping of nuclear chromatin
Most common types of cellular injury
Ischemic
Hypoxic
Reperfusion injury
When blood flow is restored to cells that have been previously ischemic, injury can be excerbated.
What is the first effect of Hypoxia
Loss of oxidative phosphorylation and ATP generation by mitochondria
When the changes in the cell caused by Hypoxia can reverse
When oxygenation is restored
What happens when ATP depletion continuous
Membrane dysfunction
Mitochondrial membrane damage
What causes the release of cytochrome c
ATP depletion
What is the result effect of loss of the membrane integrity
Massive influx of Ca
Which will inhibit the cellular enzymes denaturation of proteins and cytologies alterations characteristic of coagulation necrosis.
Effects of Free Radicals to cell to cause injury
Lipid peroxidation of membranes
Oxidative modification of proteins
Damage to DNA
Which series of enzymes act as a free radical scavenging systems
Catalase
Superoxide dismutase
Glutathione peroxidase
How does chemicals cause cellular injury
1- Directly by binding to critical molecular component
2- Indirectly by conversion to reactive toxic metabolites
Sometimes: CCL4, Acetaminophen
Which mechanisms remove free radicals and minimize cellular injury
Antioxidants
Binding of the ions to storage and transport proteins
What are the marks of the irreversible injury
Mitochondrial vacuolization
Extensive damage to cell membranes
Swelling of lysosomes
the appearance of large amorphous densities in mitochondria
Injury of lysosomal membranes result with
Leakage of enzymes into the cytoplasm and by their activation to enzymatic digestion of cell and nuclear components
What are the processes that cause the basic morphological changes of necrosis
Denaturation of proteins
Enzymatic digestion of organelles and other Cytosolic components
Pyknosis
Small dense nuclei
Karyolysis
Faint dissolved nucleus
Karyrrhexis
Nucleus broken up into many clumps
Dystrophin Cacification
Necrotic cells may attack calcium salts in the form of glandular basophilic deposits
What are the types of necrosis
Coagulation necrosis
Liquefaction necrosis
Caseous necrosis
Fat necrosis
Fibrinoid necrosis
What is Coagulation necrosis
Most common type
Characterized by denaturation of cytoplasmic proteins with preservation of the framework of the coagulated cell
Occurs in myocardium, kidney, liver…
What is Liquefaction necrosis
Occurs when autolysis and heterolysis prevail over protein denaturation
Necrotic area is soft and filled with fluid
Mostly seen in localized bacterial infections and in brain(?)
Caseous necrosis
Characteristics of TUBERCULOSIS lesions
Appears grossly as soft friable material
Microscopically as amorphous eosinophilia material with cell debris
Fat necrosis
Necrosis in adipose tissue
Induced by the activation of lipases then complex with Ca to create Ca soaps
What is Fibrinoid Necrosis
Special form of necrosis seen in immune reactions involving BV
Occurs when compexes of ag and ab are deposited in the walls of arteries
Fibrin leakage
