Acute inflammation Flashcards
What are the cardinal signs of acute inflammation?
- Rubor
- Tumor
- Calor
- Dolor
- Function laesa
What causes acute inflammation?
- Physical agents: trauma
- Chemical agents corrosive acids/alkalis
- Deprivation of blood supply
- Living organisms (infection)
- Antigen-antibody reaction - damage caused by immune complexes
What are the stages of acute inflammation
Vascular response
Changes in blood flow
Inflammatory exudate
Suppuration
What happens during the vascular response of acute inflammation? (e.g. during acute traumatic gingivitis)
Intial vasoconstriction followed by prologined vasodilatation.
1st arteriol dilatation via central channels
2nd precapillary sphincters open to allow blood pass via capillary bed & vessels
this increases warmth, size and hyperaemia
What are the changes in blood flow during acute inflammation?
- Speed of blood increases but soon diminishes
- Cells travel through central zone of venules leaving a clear cell free zone adjacent to endothelium
- Stasis - clear zone becomes occupied by numerou white blood cells = margination of white cells
- Soon becomes pavemented by them as cells becomes stickier
- Gaps appear between where fluid and plasma protein can move
- White cells whic strike the endothelium by chance are dragged back and retained (mostly polymorphs)
- Push pseudopodia between adjacent endothelial cells, penetrate basement membrane and emerge on external surface of venule = emigration of white cells
- Gap in vessel wall closes up behind them
- Few red blood cells may be forced out by hydrostatic pressure = diapedesis of red cells
What is inflammatory exudate?
Collection of fluid in extravascular tissues consisting of fluid and cellular exudate.
Formed as a result of increased permeability of vessel wall to plasma membrane (causes swelling)
What are the types of fluid exudate?
- Serous: mild inflammation, clear relatively low protein content e.g. in blister
- Fibrinous: rich in protein, especially fibrinogen, when enters tissues it clots due to formation of fibrin (e.g. pleurisy of lung in bacterial pneumonia.
- Suppurative (purulent): rich in neutrophils clinically known as pus
What are the functions of fluid exudate?
- Exudate dilutes irritant substance (consitiuents of plasma pour into area including natural antibaccterial substance.
- Form fibrin clot which forms union between several tissues as in a cut, may form barrier against bacterial invasion and aids phagocytosis.
What is cellular exudate?
Cells accumulate into extravascular space via vessel wall (chemotaxis) at same time as fluid exudate forms.
Cells are polymorphs and monocytes. After a few days polymorph undergo necrosis.
What are the functions of cellular exudate?
- PHAGOCYTOSIS (PMNL) 2 MACROPHAGES INTIATE IMMUNE RESPONSE BY PROCESSING ANTIGEN
What aids phagocytosis?
Opsonisation & Surface phagocytosis
How does opsonisation aid phagocytosis?a
- Opsonins are proteins that coat organisms and cause them to be more easily phagocytosed.
- There are:
- non-spefici opsonins
- Immune opsonins which are a type of antibacterial antibody
What is surface phagocytosis?
- Phagocytes eg PMNL ingest organisms by engulfin growing pseudopodia around it
- Degranulation
- Digestive lysosomal enzymes of granules poured into vesicle which organisms is contained
- PMNL release pyrogen (causes fever)
- Pinocytosis? incorporates fluids or dissolved substances
Why may tissue damage occur in primary inflammation?
During degranulation of PMNL (surface phagocytosis) Neutrophil granules in PMNL contain proteolytic enzymes (elastase, colagenase & gelatinase) that destry matrix which surrounds connective tissue cells and forms basement membrane. When this matrix is destroyed irreversible tissue damage occurs.
What is pus?
Creamy fluid contained within an abscess containing leukocytes, living and dead fluid exudate, fibrin, organisms (living and dead), tissue debris e.g. nucleic acids and lipids.
