Unit 9 - Cell death and adaptation Flashcards
What causes different levels of tissue recovery?
Cellular injury - tissue function dependent on number of cells affected
Cell death - tissue with regenerative capacity and ECM undamaged, recovery to normal
Tissue regenerative capacity, but ECM damaged = permanent damage
What are the common causes of cellular injury?
-Lack of factors needed for normal cell function: blood, oxygen, nutrients, neural stimulation
- Physical: trauma, heat/cold
- Chemical: drug injury
- Inflammation: Autoimmune inflam
- Metabolic and genetic disorders: diabetes mellitus, obesity, glycogen storage disease
What determines the cell’s susceptibility to ischaemia or hypoxia?
Cell metabolic rate and anatomical position to arterial supply
How may cell injury or death present clinically?
Deranged tissue/organ function
Leaked intracellular contents in blood detected
How may cell injury/death present pathologically?
Morphological changes in tissue
Gross changes in surgical specimens
Light microscopic changes
How may cell morphology change in sublethal (reversible) cell injury?
Cell swelling:
Na/K+ pump failure = water influx
Membrane and organelle changes seen under EM
Fatty changes:
Deranged metabolism -> lipid accumulation intracellularly
What are the two main types of cell death?
Apoptosis:
Physiological process, specific enzymes break down cells, neat, normally single cells
Necrosis:
Not physiological, uncontrolled cell breakdown, non-specific enzyme activation, messy, large groups of cells
Name the two main patterns of necrosis
Coagulative
Liquifactive
Coagulative necrosis process
Most common
Leakage of cell contents from membrane breakdown
Inflammatory cell response
Leukocyte lysosomal enzymes are major factor in cell digestion
Macrophages are attracted and phagocytose and initiates granulation tissue
What is the gross appearance of coagulative necrosis?
Pale yellow from acute inflam cells
If blood flowing to tissue:
Haemorrhage
Acute inflammation
Infarction if dual blood supply
What does liquefactive necrosis arise from?
Focal bacteria and fungal infections
What are the features of liquefactive necrosis?
Abscess
No normal structures apparent
Soft disintegrating tissue
What are the possible outcomes of necrosis in different tissue types?
Tissues able to regenerate:
ECM intact -> return to normal
ECM damaged -> repair and scar
Tissues no regenerative capacity:
-> repair and fibrous scarring
Apoptosis
Cell death occurring normally through life
Elimination of unwanted cells/cells damaged beyond self repair
Cell death without host reaction
Programmed and controlled cell death
What does the morphology of apoptosis look like under a light microscope?
Darker staining small round bodies
Small black/very black shrunken fragments of nucleus
