Inflammation Flashcards
What is the purpose of inflammation?
A reaction to infection or tissue damage that delivers leukocytes and plasma proteins to the site of injury to prevent further damage
Vascular dilation
One of the earliest signs of acute inflammation
A rapid increase in blood flow results in heat and redness
Induced by histamine, bradykinin and nitric oxide
Cardinal signs of inflammation
redness, heat, pain, swelling, loss of function
Permeability changes
Inflammation causes the microvasculature to become more permeable
This allows plasma proteins and leukocytes to leave the circulation and causes swelling
It is achieved by endothelial cells contracting and detaching and an increase in transport through endothelial cells
Accumulation of leukocytes at injury site
Leukocytes that accumulate at the damaged tissue do so by extravasation/diapedesis
This is achieved by adhesion molecules and chemotaxis
Chemoattractants
Common chemoattractants include bacterial products, complement components, cytokines and products of the lipooxygenase pathway
Downstream effects of inflammation
- Phagocytosis at the infection side
- Opsonisation of the pathogen
- Destruction of microbes by anti-microbial pathways
- Activation of the kinin, clotting and fibrinolytic pathways
Kinin system
Activated following tissue damage by Hageman factor (XII)
Factor XII activates prekallikrein to form kallikrein
Kallikrein cleaves kininogen to form bradykinin
Bradykinin causes vessel dilation, increased vascular permeability and smooth muscle contraction
Fibrinolytic system
Activated by Hageman factor (XII) which activates a cascade that produces plasmin
Plasmin breaks down fibrin clots, activates enzymes required for collagen remodelling and promotes angiogenesis
Clotting system
Activated by Hageman factor (XII) which leads to a cascade that results in thrombin production
Thrombin leads to clot formation, activates platelets and causes the release of fibrinopeptides
