Cell Response to Injury: Morphological Changes 1 Flashcards
Why is it important for cells to be dynamic?
Because they are exposed to constant change, so they need to be able to adapt to limited stress exposure
When is the change reversible?
When limit is not exceeded
When is the change irreversible?
When that limit has been exceeded
What happens when the change is outside the acceptable limit?
It leads to disease
What sort adaptations occur when cells are adapting to environmental change?
Physiological structural adaptations – change in normal pattern of growth and detectable structural changes
Why do reversible functional and structural responses occur?
To achieve a new altered steady state
How do cells adapt?
- Increased cellular activity
- Decreased cellular activity
- Alteration of morphology
What do these adaptations result in?
A new altered state is achieved which better equips the cell to survive
What does cell injury result from?
Functional and biochemical abnormalities in one or more of several essential cellular components
What causes the varying susceptibility between cells sensitivity to injury?
Ability to survive ATP depletion - ATP loss causes failure of biosynthesis and membrane pumps
Ca2+ influx - Free calcium in the cytosol activates intracellular enzymes cause destruction
Reactive oxygen species (ROS) - Disturb normal cell function & damage cell components
What are the main targets of damaging stimuli (4)?
- Mitochondria
- Cell membranes
- Cytoskeleton
- Cellular DNA
what are the 2 types of cell damage?
- sub-lethal injury
- lethal injury
what is sub-lethal injury?
- If damage is minimal, cell recovers after removal of damaging stimulus / REVERSIBLE
- Associated with reversible structural abnormalities
what are the characteristics of sub-lethal injury (3)?
- Cell and organelle swelling
- Blebbing of plasma membrane
- Detachment of ribosomes
how are the features of sub-lethal injury seen?
can be recognised by a light microscope
what are the features of sub-lethal injury?
• Hydropic degeneration/cellular swelling
▫ Disruption of ionic fluid and fluid homeostasis
▫ Failure of energy dependent membrane pumps
• Fatty change
▫ Hypoxic, toxic or metabolic injury
▫ Manifested as lipid vacuoles in cells
what causes hydropic degeneration?
the swelling of organelles which leads to cellular swelling
what are the characteristics of hypdropic degeneration (3)?
- Cytoplasm becomes pale
- Formation of intracellular vacuoles
- Called ‘cloudy swelling’
what causes fatty change?
Accumulation of lipids in cells:
• Toxins
• Hypoxia
• Disease
what are the characteristics of fatty change (5)?
- Cells accumulate lipid in cytoplasmic vacuoles
- Effects cells that have key role in FA metabolism
- Affected organ is enlarged
- Yellow in colour
- Vacuoles can coalesce to form ‘fatty cysts’
what is lethal injury?
• Caused by severe damaging stimulus or prolonged sub-lethal damage IRREVERSIBLE
• Cell death occurs by –
▫ Necrosis
▫ Apoptosis
what determines the type of cell death?
- Magnitude/type of injurious stimulus determines the type of cell death
- Availability of cellular ATP after damage
how can necrosis be described?
Denaturation of proteins and enzymatic digestion
what are the characteristics of necrosis (5)?
- Loss of plasma membrane integrity
- Activation of lysosomal enzymes
- Enzymatic digestion of cells by autolysis
- Leakage of cellular constituents inflammation
- Necrosis of tissue has distinct patterns
