Week 1: Cell death and adaptation Flashcards
What is the cellular injury?
The non-lethal response to a damaging agent, results in a loss of normal functioning.
What are the potential outcomes of cellular injury?
Cellular injury may be short lived hence reversible
Alternativly cell injury can be prolonged, leading to cell death.
What factors affects the amount of function lost as a result of cellular injury?
The number of cells, and the extend to which these cells are injured
In what scenarios can tissue injury lead to tissue death?
- Extensive cellular injury so looses regenerative capacity
- Tissue retains regnerative capacity but the ECM has severe damage, so damage is permanent and function reduced
What are some common causes of cellular injury?
- Lack of factors essential for normal cell function
- ischemia/hypoxia
-nutrient deficiency
-neural stimulation - Physical - trauma, temperature
- Chemical - drugs, toxins
- Inflammation (may be autoimmune)
5, Metabolic and genetic disorders - diabetes and obesity
What affects a cells susceptibility to injury?
Metabolic rate
Anatomical position
For examples cells most vulnerable to hypoxia tend to have a high oxygen demand and are located far away from the nearest blood vessel
Do all cells in a tissue respond equally at the same time to a given injury?
No due to different suspectibility to that injury
Some cells will take longer to be injured or killed by that stimuli
What are the clinical methods of detecting cell injury and death?
Presentation of symptoms in the patient, due to decreased tissue/organ function
Blood test may detect leaked intracellular contents when severe membrane damage has occured
What are the pathological ways of detecting cell injury and death?
Morphological changes in the tissue
Light microscope changes
Gross changes in surgical speciemens
What is sublethal cell injury?
Cell injury that is reversible
What are the common morphological changes in sublethal cell injury?
Cell swelling - in all cells
Fatty changes - only is some cell types mainly hepatocytes
What is the mechanism causing cell swelling in cellular injury?
shown by all cell types, Na/K+ pump failure,
intracellular Na+ conc increases,
intracellular environment has a higher concentration of solutes, causing inward movement of water by osmosis.
Cell swelling is visible on the light microscope
This causes damage to the membrane and organelles that is only visible under the electron microscope
What is the mechanism causes fatty changes in cellular injury?
Causative factors: alcohol, toxins, hypoxia, obseity, malnutrion and altered metabolism in diabetes
Intracellular accumulation of lipid due to deranged metabolism
Results in disruption of aerobic glycolysis and beta oxidation of fats
What is another term used to describe cellular swelling of hepatocytes during cellular injury>
Hepatocyte ballooning
How can cellular swelling be identifed?
In light microscope - increased cytoplasm size, typically cells appear paler stained and loose characteristic shape
Electron microscope may also detect damage to cell membrane and organelles
How can lipid accumulation in hepatocytes be identified?
Liver is often enlarged and yellowed in colour
Fat droplets can be seen in histological images of hepatocytes
What are the two different types of cell death?
Apoptosis
Necrosis
What are the key features of apoptosis?
Programmed cell death
Is a physiological process - hence is neat and tidy
Requires the activation of specific enzymes often caspases
Normally only occurs in single cells
Maintains tissue function
Results in unwanted cells or cells injured beyond repair.
What are the key features of necrosis?
Is pathological
Is uncontrolled breakdown by non specific enzyme activation
hence is messy and typically affects a larger group of cells
Is very common after injury.
What are the two different morphologies of necrosis?
Coagulative
Liquifactive
What are the features of coagulative necrosis?
Most common morphology of necrosis
Injury thoguht to damage structural proteins and enzymes so blocks breakdown of dead tissue.
Causes slower shrinking of cells.
Tissue architecture can be preserved but in a weak and non-functional way.
Cystoplasm becomes opaque and cell outlines still visible
Commonly caused by ischemic conditions