*Pathology (2) Flashcards
Why are mediators of inflammation short lived?
They are only produced as long as the stimulus is present
How long do neutrophils survive outside of a blood vessel?
A couple of hours
What are the 4 possible sequels after acute inflammation`?
Resolution Suppuration Repair, organisation, and fibrosis Chronic inflammation *may not be mutually exclusive
what does what one of the 4 possible sequels of inflammation that occurs depend upon? (3)
Site of injury (different organs have different capacities for repair and different vascular supplies)
Type of injury (severity, pathogenicity of organism)
Duration of injury (can be removed, is it sustained)
What is resolution?
Complete restoration of the tissue to normal after removal of inflammatory components
How much cell death occurs with resolution?
Minimal amounts
What kind of tissues does resolution occur in?
Tissues that have capacity to repair e.g GI tract
Tissues that have a good vascular supply for delivery of WBCs and removal of injurious agents
What is suppuration?
Formation of pus
What is pus formed from?
Living, dying and dead cells (neutrophils, bacteria and inflammatory debris (fibrin))
What is an abcess?
Collection of pus
What is an empyema?
A collection of pus in a body cavity
When does repair occur
When a tissue is injured and cannot be wholly regenerated
What are the 3 phases of repair?
Phagocytosis to clear debris
Organisation
Epithelial regeneration to cover wound
When does repair occur in contrast to resolution? (4)
When injury produces lots of necrosis
if injury produces a lot of fibrin that isn’t easily cleared
if there is a poor blood supply = difficulty removing debris
Mucosa where damage goes beyond the basement membrane favours healing by organisation and repair and not resolution (substantial tissue damage meaning the tissue is unable to regenerate and is instead replaced by fibrous tissue - resolution occurs a scaffolding to occur)
What is organisation?
Fibroblasts secrete ECM and new vessels grow into region -> formation of granulation tissue
What happens in granulation tissue formation? (organisation)
Defect is slowly infiltrated by capillaries and then by myofibroblasts
Deposit collagen and smooth muscle cells
Has a very red look
What is fibrosis?
Formation of excess fibrous connective tissue in an organ/ tissue in a reparative/ reactive process
If this is in response to injury it is called scarring
“patch job”
Causes a loss of function
When does scarring and fibrosis of the liver occur?
Liver can regenerate but if overwhelmed it undergoes scarring and fibrosis = cirrhosis resulting in liver failure
When is chronic inflammation favoured?
Suppuration
Persistence of injury e.g. foreign material
Persistence of infection
type of injury e.g. autoimmune, transplant rejection
What is chronic inflammation characterised by?
Lymphocyte
Macrophage (monocyte within tissue)
What is a granuloma?
A collection of immune cells known as histiocytes
“aggregate of epithelia histiocytes”
What is a histiocyte?
A stationary phagocytic cell present in connective tissue
When does a granuloma form?
When the immune system attempts to wall off substances it perceives as foreign but is unable to eliminate
e.g. endogenous - keratin, bone, crystals
Exogenous - talc, asbestos, suture materials, oil
What are some examples of diseases that cause granulomas?
Specific infections Parasites Worms Eggs Syphilis Mycobacterium - including TB
