Acute Inflammation Flashcards
What is inflammation and what is its aim?
it is protective response to injury
it aims to rid the body of the initial cause of injury and the consequences of such injury
What suffix indicates that inflammation is present?
itis
What is acute inflammation and how long does it last for?
it is the initial tissue reaction to injury
it is short-lived - mins, hrs, days
What is the characteristic cell of acute inflammation?
the neutrophil polymorph
What will acute inflammation deliver to the injured site?
White cells and plasma proteins (e.g. antibodies)
What are the 5 physical characteristics of acute inflammation?
- redness (rubor)
- heat (calor)
- swelling (tumor)
- pain (dolor)
- loss of function (functio laesa)
What are the 5 main causes of acute inflammation?
- physical agents
- infection
- hypersensitivity reactions
- chemicals
- tissue necrosis
What are examples of physical agents that can cause acute inflammation?
thermal injuries e.g. burns, frostbite
physical trauma
How can a hypersensitivity reaction cause acute inflammation?
the immune system damages the individual’s own tissues
this is persistent and difficult to cure as the stimulus cannot be removed
What is involved in the fibrinous reaction of the inflammatory response?
Fibrinogen leaks out of the blood vessels and comes into contact with extracellular tissues where it forms fibrin strands
What is the consequence of serous inflammation?
thin fluid from plasma or mesothelial cell secretions
accumulation of fluid results in effusion
What are the 3 major components of acute inflammation?
- changes in vessel calibre
- increased vascular permeability and fluid exudate formation
- cellular exudate formation
Why do vessels undergo changes in acute inflammation?
to maximise the movement of plasma proteins and cells into the site of injury
What causes most of the swelling in acute inflammation?
the fluid exudate
the cellular exudate only contributes slightly to the swelling
What is the definition of exudate?
extravascular fluid with high protein concentration, containing cellular debris
it implies inflammation
What is the definition of transudate?
extravascular fluid with low protein concentration and little or no cellular component
What is the definition of oedema?
excess fluid in the interstitial tissue/serous cavities
this can be exudate or transudate
What is the definition of pus?
inflammatory exudate rich in neutrophils, dead cell debris and microbes
What is the initial change in vessel calibre at the onset of acute inflammation?
There is a very short initial transient vasoconstriction
What happens after the initial transient vasoconstriction?
Vasodilation that lasts from 15 mins to several hours
What is the result of vasodilation in acute inflammation?
it increases blood flow to the injured area by up to 10 times
this produces heat and redness
How is vasodilation in acute inflammation mediated?
by histamine and nitrous oxide on vascular smooth muscle
What causes formation of the fluid exudate?
increased permeability of microvasculature results in the escape of protein rich fluid into the tissue
What are the 3 main causes of fluid exudate formation?
- chemical mediators - histamine, NO and leukotriene
- direct vascular injury
- endothelial injury
Normally, how does hydrostatic pressure vary in the capillary beds?
High hydrostatic pressure at the arteriole end due to plasma proteins forces fluid out
The fluid returns to the vessel at the venous end, where hydrostatic pressure is low
In acute inflammation, how does hydrostatic pressure in the capillary beds change?
There is increased hydrostatic pressure, meaning fluid cannot return at the venous end
Plasma proteins escape into the extravascular space, increasing osmotic pressure
This leads to exudation - more fluid leaving the vessel
How does the fluid exudate help with treatment of acute inflammation?
It allows for transport of drugs to the injured area
Increased blood flow allows drugs to rapidly reach the injured area