Flashcards in P2- Injury, Healing and Repair Deck (46)
Name the causes of cellular / tissue injury.
-Physical - mechanical , thermal ,electric , Barotrauma
-Chemical - drugs , metabolic , hypoxia , nutrition
-Infectious - cytolysis , toxins , immune response
-Immunological -may contribute to other categories
-Genetic -may contribute to other categories
What can. cause cellular injury?
Describe mechanics by which cell injury manifest , at a cellular level.
Mechanisms by which cell injury is manifest may be very similar for different causal agents
what are the different phases of cellular injury?
what is cellular injury recognised by?
-morphological / Structural features
what does severe damage in cellular injury lead to?
What are the vulnerable intracellular systems of mechanics of cellular injury?
-Cell Membrane Integrity
-Protein Synthesis :
what is closely related in mechanisms of cellular injury?
structural and biochemical aspects
what are types of mechanics of cellular injury?
-deficiency of metabolite (o2)
-impaired metabolism (respiration and syntheis e.g of proteins)
-Membrane damage (structural -physical/chemical, functional- failure of ion pumps , calcium ion homeostasis )
-DNA damage or loss (radiation, drugs, free radicals)
describe disruptions to membrane integrity.
Physical trauma, osmotic, freezing, complement, cytotoxic proteins in Tc cells
Depletion of ATP, alterations to lipids and protein in the cell membranes e.g. cross linking induced by free radicals
-CSM and internal membranes.
Describe impaired metabolism.
-Lack of oxygen e.g blood supply, CO
-Block mitochondrial respiratory chain e.g. cyanide binding to cytochrome oxidase
-Ricin blocks translation at ribosome
-Decreased ATP will contribute
Describe DNA damage / loss.
-May not be immediately apparent
-Dividing cells particularly affected – or when there is a growth stimulus
-Non-lethal damage may introduce heritable abnormality that can lead to disease in daughter cells e.g. neoplasia
Highly reactive and chemically unstable species
Describe metabolite deficiency.
Any essential metabolite:
-Anaerobic pathways induce acidosis
-Ischaemia and infarction
-Some cells have high requirements and sensitive to deficiency.
-Diabetes mellitus - poor utilisation - absolute or relative deficiency of insulin
-Lack of trophic hormones leads to target cell atrophy
what does the severity of damage and the effects on the cells and tissues depend on?
-Type, magnitude and duration of injury
-The type of tissue affected
-The proportion / numbers and types of cells affected
-The effect on the connective tissue scaffold
-The effect on other tissues and structures e.g. blood vessels
what are the stages of cellular insult?
-reversible cell injury (loops to adaptive response and normal cell)
-irreversible cell injury
what occurs in reversible damage?
-Reduced aerobic respiration
-Increased anaerobic respiration
-Membrane pumps fail
-Accumulation of lipids
what is the recognition of cell injury?
Cell swelling (Hydropic change) :
-Cytoplasm pale and swollen
-Accumulation of fluid
-Function of membranes and membrane pumps affected
-Hypoxia and chemical poisons
Fatty change :
-Accumulate lipid droplets
-Uncoupling of lipid and protein metabolism
-Liver commonly affected
-May see many small vacuoles or one large vacuole
(Both of these events are usually reversible )
what is irreversible damage characterised by?
-Severe damage to cell membranes
-Severe damage to mitochondria
-Leakage of enzymes
what happens in irreversible damage?
Cell Membrane Damage;
-Progressive Loss of Phospholipids (Increased Degradation, Reduced Synthesis)
- Lipid Breakdown Products
what are the 2 types of cell death?
Apoptosis : pre-programmed (decides itself)
Necrosis : pathological cell death
Describe features of apoptosis.
-Affects scattered cells: Cells shrink , Apoptotic bodies form, No inflammation
Stereotyped sequence of events , Biochemical regulation (Inducers /Inhibitors)
Describe features of necrosis.
-Affects sheets of cells : Cells swell , Dissolution of organelles, Inflammation
-Not energy dependent
-Descriptive terms : Coagulative, Colliquitive Caseous , Fibrinoid
what is involved in apoptosis?
-Molecular mediators and regulators
-increased apoptosis (AIDS)
-decreased apoptosis (Neoplasia)
what is the outcome of complete repair after injury and damage?
what is the outcome of incomplete repair after injury and damage?
what is the outcome of cell injury affected by?
The type of cell affected:
-Adaptive capability of cell affected
The damaging agent:
-Duration / Severity of exposure
-Damage that affects structures required for healing eg blood vessels with radiation
Other host factors
what are the classifications of cell types?
GI Tract, Bone Marrow
Neurones, Skeletal Muscle
what are cells that are lost replaced by?
a pool known as stem cells
where are stem cells located?
in discrete compartments