Cell Death Lecture Flashcards
Define necrosis
spectrum of morphologic changes that follow cell death, largely resulting from the progressive degradative action of enzymes on the injured cells
What is irreversible cell injury associated with?
Severe swelling of the mitochondria, extensive damage to cell membrane and swelling of lysosomes
What does damage to the lysosomal membrane cause?
Leakage of lysosomal enzymes into the cytoplasm which are activated by calcium and other factors –> autodigest the cell and produce extensive damage
What causes swelling?
Sodium pumps shutting down and accumulation within the cell
What are some cellular histological changes common to early necrosis?
Increased eosin (acid) staining (loss of basophilic mRNA)
Glassy homogenous appearance of cytoplasm (loss of glycogen particles)
Vacuolated or “Moth Eaten” cytoplasm (enzymes with digestive organelles)
Calcification (accumulated calcium)
What do necrotic cells look like under electron microscopy?
Discontinuous membrane
Dilation of mitochondria
Intracytoplasmic “myelin” bodies
Aggregates of fluffy material in cytoplasm (denatured proteins)
What are some morphological changes in necrosis?
Swelling of cell, disruption of lysosomes and cellular membrane, nuclear condensation, fragmentation and dissolution of the nucleus
What is pyknosis?
Nuclear condensation
What is karyolysis?
Dissolution of the nucleus
What is karyorrhexis?
Nuclear fragmentation
Define coagulative necrosis
Result from injury and following acidsosi that denatures proteins and enzymes (blocks proteolysis)
What is coagulative necrosis characterized by?
Preservation of the basic outline of the cell and firm texture of the tissue
Define liquefactive necrosis
Where there is accumulation of inflammatory cells
Involves complete digestion of dead cells leaving liquid viscous mass
What is liquefactive necrosis characterized by?
Local bacterial or fungal infections or hypoxic cell death in the nervous system
Accumulation of dead white cells (pus)
Define fibrinoid necrosis
Occurs when antigen and antibody complexes accumulate in the artery wall
Define caseous necrosis
Tissue architecture is completely obliterated
Tuberculosis
What is caseous necrosis characterized by?
White, cheesy appearance marked by amorphous granular debris
Define fat necrosis
Descriptive of focal areas of fat destruction which occurs as a result of pancreatic lipases into the pancreas and peritoneal cavity (acute pancreatitis)
Define apotosis
Is the end-point of an energy-dependent cascade of molecular events initiated by certain stimuli
A distinct form of cell death mediated through activation of a coordinated, programmed series of cell events
When is apoptosis common?
Development Hormone dependent (menstrual cycle) Continuously proliferating cell populations (tumors) Certain viral disease (hepatitis) Stimuli (radiation, heat , etc)
What are the three phases of the apoptotic pathways?
Decision phase
Commitment phase
Execution phase
What is the decision phase?
Cell receives a stimulus and depending on both its internal and external environments may or may not trigger to die
What is the commitment phase?
Cell is committed to death and cannot recover
What is the execution phase?
Cells activate apoptotic machinery leads to morphological changes that define apoptotic cells
Activates enzymes to carry out cell death
