What is acute inflammation?
A fundamental response maintaining the integrity of an organism
A series of protective changes occuring in living tissue as a response to injury
What are signs of acute inflammation?
Loss of function
What are possible aetiology (causes) of acute inflammation?
Mechanical (trauma to tissue)
Chemical (acid or alkali)
Physical (extreme heat, cold or ionisation)
Where does acute inflammation happen?
Localised to affected tissue
What is the process of acute inflammation?
Series of microscoping changes that take place in the circulation
What is the microcirculation composed of?
Capillary beds (fed by arterioles and drained by venules)
Extracellular space and fluid
Lymphatic channels and drainage
What does the flux of fluids across the microcirculation depend on?
The difference in pressure in and out pulling the fluid in opposite directions (hydrostatic and cologenic pressures)
What does acute inflammation lead to in the microcirculation?
Changes in vessel radias (flow)
Changes in permeability of the vessel wall (exudation)
Movement of neutrophils from the vessel to the extracellular space
What are the changes in vessel flow known as?
What is the process of the triple response?
1) Temporary arteriolar constriction (protective)
2) Local arteriolar dilation (active hyperaemia)
3) Relaxation of vessel smooth muscle
What is flow proportional to?
Radias to the power of 4
What does a small increase in a vessel radias lead to?
A massive increase in flow
What symptoms does the increased flow cause?
Redness and heat
What does increasing vessel permeability result in?
Net movement of plasma from capillaries to extravascular space
Increased viscocity which decreases flow
What does increased viscocity cause?
White blood cells to travel to the edge of the vessel and the erythrocytes to the middle, which is the opposite to how they normally are
What is exudation?
Process of increasing the vessel permeability
What is exudate?
The fluid that leaks from a vessel during exudaiton, rich in protein including immunoglobulin and fibrinogen
What does exudation result in?
Formation of oedema, which explains the swelling which causes pain and reduced function
What is oedema?
Accumulation of liquid in the extracellular space
What are the phases of the emigration of neutrophils?
1) Migration (moves to edges of lumen)
2) Pavementing (adhere to the endothelium)
3) Emigration (squeeze between endothelial cells to the extravascular space)
What are some examples of diseases caused by inflammation?
What is the ideal outcome of acute inflammation?
Inciting agent isolated and destroyed
Epithelial surface regenerates
Exudate is filtered away
Vascular changes return to normal
What are the benefits of acute inflammation?
Rapid response to nonspecific insult
Neutrophils destroy organism and denature antigen for macrophages
Plasma proteins localise process
What are the possible outcomes of acute inflammation?
Suppuration (pus formation)