CAM101- Cell Injury and Cell Death Flashcards
Hydropic swelling?
Definition: Hydrophobic swelling reflects acute reversible cell injury.
Reversible cellular damage. It involves the impairment of volume regulation (a process that controls ionic concentrations in cytoplasm) leading to fluid accumulation.
Injurious agents cause:
Increased membrane permeability (to sodium, thereby exceeding the capacity of the pump to extrude sodium)
Damage to Na+/K+ pump:
Interfere with ATP synthesis (thereby, depriving the pump of its fuel)
The accumulation of sodium- increases water content- cell swells
Common causes: Chemical and biological toxins Viral or bacterial infections Excess heat or cold Ischemia
Factors to be considered of cellular response to a damage to its integrity
Type of injury
Duration
Severity or extent
Past consequences: Cell type Pre-existing state of cells/tissue prior to the damage Adaption response
Fatty change?
Definition: a reversible cell adaption/injury. it consists in lipid accumulation and thus, formation of vacuoles within the cytoplasm.
Common causes:
Toxins (eg. Ethanol)
Chronic hypoxia
Diabetes mellitus
Mitochondrial changes?
Definition: reversible cellular damage, involving:
Swelling
Rarefaction- decrease in numbers
Amorphous densities- phospholipid rich (particularly common in
sacrolemma)
Endoplasmic Reticulum Disruption?
Definition: Reversible cell injury that concerns the dilation of the cisternae are dilated by excess fluid.
Results:
Dilation
Polysomic disaggreation (detachment of ribosomes)
Accumulation of free ribosomes in cytoplasm
Membrane Blebs?
Definition: focal extrusion of the cytoplasm
What does cell damage result from?
Factors: Mechanical damage (trauma) Failure of membrane integrity Damaged metabolic pathways DNA damage or loss Deficiency of essential metabolites Generation of oxygen-derived free radicals
What is Cell Death?
-Accidental and Programmed
Consists if irreversible cessation of all cellular functions.
Accidental: Irreversible morphological changes to a cell or group of cells or a tissue (of an organ) following and internal or external insult.
Programmed (apoptosis): follows normal physiological processes or as the result of irreversible cell injury.
General Overview of the Mechanisms of Cell Injury
All cells have efficent mechanisms to deal with shifts in environmental conditions and thus, maintain homeostasis.
Ion channels opening and closing
Harmful chemicals are detoxified
Metabolisation of fat or glycogen stores
it is when environmental changes exceed the cell’s capacity to maintain normal homeostasis that acute cell injury. If the stress is removed in time or if the cell can withstand the assault, cell injury is reversible, and complete structural and functional integrity if restored. Conversely, if the cell cannot withstand, irreversible injury leads to cell death.
Define: Necrosis
It is the combination of all morphological phenomena observed in cells or tissues, followed by death (cells/tissues) taking place in a living organism.
The morphological changes indicative of cell death caused by progressive enzymatic degradation.
Cell/tissue death is not the same as cell/tissue necrosis
Coagulative Necrosis
Type of accidental cell death
Typically caused by ischemia or infarction
Structural architecture is preserved
Homogeneous, glassy eosinphillic appearance due to loss of RNA and glycogen
Cell outlines are preserved- everything else is eosinphilic (red)
Firm consistency
Denaturing of structural proteins and enzymatic digestion of cells
Initiating Mechanisms of Coagulative Necrosis
ATP deficiency
Impairment of calcium homeostasis
Toxic oxygen metabolites (oxygen free-radicals)
Cell membrane damage
Morphology of Coagulative Necrosis
Occurs in a fresh specimen
MACROSCOPIC:
yellowish, dry, mortar-like mass, firm texture
MICROSCOPIC: Reduced tissue transparency Perseveration of temporary cellular contour Indistinct tissue delineation Increase eosinphilia
Sequence of Events in Coagulative Necrosis
KARYOPYKNOSIS: Condensation of chromatins; reducing size of nucleus
KARYORRHEXIS: fragmentation of the nucleus
KARYOLYSIS: disappearance of nucleus
Liquefactive Necrosis
Digestion of dead cells becoming a viscous mass
Affect organ will lose part or total morphological features
Increased rate in necrosis tissue dissolution
Liquid viscous mass (pus)
Common in infections due to the presence of lots of neutrophils releasing their toxic contents (enzymes) thus, ‘liquefying’ the tissue.
