Acute inflammation Flashcards
Define acute inflammation?
inflammation
-fundamental response
-dynamic, homeostatic mechanism
-you find a series of protective changes occurring in living tissue as a response to injury
Name the cardinal signs of inflammation?
rubor - redness, darkening
calor - heat
tumor - swelling
dolor - pain
loss of function
List the causes of acute inflammation?
-micro-organisms
-trauma
-exposure to chemicals
-physical- extreme conditions
-dead tissue (cell necrosis irritates adjacent tissues)
-hypersensitivity
What is the microcirculation?
All over us
It is the capillary beds, fed by arterioles and drained by venules but also the extracellular compartment - fluid and molecules within it.
Also includes the lymphatic channels and lymphatic drainage channels.
Occurs in a dynamic balance- things move but in a way which is balanced
What happens in micro circulation?
fluid moves essentially from the vessels into the tissue
Pathogenesis of acute inflammation?
changes in vessel radius- alter the amount of flow through the vessel
change in permeability of the vessel wall-endothelium becomes more permissive or less permissive (exudation)
movement of neutrophils from the vessel to the extravascular space
Describe what happens with the local changes in vessel radius and blood flow?
1.transient arteriolar constriction
-transient constriction of the feeding arterials
-probably protective
2. local arteriolar dilation
-active hyperaemia
-see more blood in those vessels
-widen radius
3. relaxation of vessel smooth muscle that covers vessel wall
The triple response- goes red, redness about it and then swelling
How does increased permeability occur?
-happens in the vessels, in the microvascular bed
-caused by locally produced chemical mediators (small mols from cells) which increase permeability of endothelial cells (lining vessels) and make it leak
-When leaks, leaks fluid. Protein and fluid not held in vessel lumin- escape into adjacent tissue
Effects of increased permeability?
net movement of plasma from capillaries to extravascular space (exudation)
what is leaked is an exudate
exudate-exudate - fluid rich in protein - like plasma - includes immunoglobulin and fibrinogen
Effects of exudation?
oedema formed
oedema is accumulation of fluid in the extravascular space
explains swelling of tissue in acute inflammation because movement of fluid across membrane
swelling causes pain - reduce function
What is a further effect of increased permeability?
fluid loss-increased viscosity
increased viscosity-stasis
got all cells in blood and less plasma holding them up and the rate of flow slows (stasis)
What happens to flow in inflammation?
loss of normal laminar flow
red cells aggregate in the centre of the lumen
neutrophils found near endothelium
What are the phases of emigration of neutrophils?
margination - neutrophils move to endothelial aspect of lumen
pavementing - neutrophils adhere to endothelium
emigration - neutrophils squeeze between endothelial cells - active process - to extravascular tissues
Describe gingivitis?
gums are swollen and inflamed
associated with certain types of acute leukaemias
Describe acute pyelonephritis?
tubules inside kidney have blood and pus coming through
Describe bacterial endocarditis?
vegetations(mix of fibrin, neutrophils and micro organisms stuck on the atrial surface - of cusp)
What happens after acute inflammation?
inciting agent isolated and destroyed
macrophages move in from blood and phagocytose debris; then they leave
epithelial surfaces regenerate (skin heals)
inflammatory exudate filters away
vascular changes return to normal
inflammation resolves
What are the benefits of acute inflammation?
rapid response to non-specific insult
cardinal signs and loss of function
transient protection of inflamed area
neutrophils destroy organisms and denature antigen for macrophages to phagocytose
plasma proteins localise process
resolution and return to normal
Outcomes of acute inflammation?
resolution
suppuration (pus formation)
organisation (tissue repair)
chronic inflammation( inflammation doesn’t go away- associated with tissue damage)
Describe the role of the neutrophil?
mobile phagocytes
-recognise foreign antigen
-move towards it - chemotaxis
-adhere to organism
granules possess oxidants (eg H2O2) and enzymes (eg proteases)
release granule contents
phagocytose & destroy foreign antigen