The initial rapid response to infection and tissue damage is called acute inflammation.
Inflammation is defined as the local response of living mammalian tissue to injury from any agent, it is the body defence reaction in order to element or limit the spread of injurious agent followed by removal of necoreised cell and tissue.
Agents causing inflammation are :-
- Infective agents – bacteria, virus, toxins, fungi etc.
- Immunological agents – cell medited and antigen antibody reaction.
- Physical agents – heat, cold, radiation, mechanical trauma etc.
- Chemical agents – organic and inorganic poisons.
- Foreign bodies
Signs of inflammation
- There are some signs of inflammation which show in every inflammation like
Events of inflammation
Acute inflammatory response by the host to any agent is a continuous process but for the purpose of disscus, it can be divided into two types i.e. Vascular events and cellular events.
In vascular events there is alternation in the micro vasculature that is arterioles, capillaries and venules. It is the earliest response to tissue injury.
Alteration include haemodynamic changes and vascular permeability.
- Transient vasoconstriction of arterioles
- persistent progressive vasodilation i.e. responsible for redness and warmth.
- progressive vasodilation – results for fluid into the extracellular space responsible for swelling.
- Slowing and stasis of micro circulation causes increase in concentration of red cells and raise blood viscosity.
- Leukocytic migration – leukocytes stick to endothelium then move and migrate through gap between endothelium cells into extra vascular space called emigration.
Lewis induced the changes in the skin of inner aspect of forearm by stroking a blent point, it is called triple response.
- Red line appears within few seconds after stroking due to vasodilation.
- flare is bright reddish appeare surrounding the red line and result from vasodilation.
- wheal is the swelling of surrounding skin due to migration of fluid in extra vascular space.
Edema donates and excess of fluid in the interstitial tissue or cavity. It can be either exceuted or transudate.
There is increase in vascular permeability.
It includes Exudation of Leukocytes and phagocytosis.
Exudation of Leukocytes – escape of leukocytes from the lumen of micro vasculature to the intestinal tissue is the most important feature of the inflammatory response.
Phagocytosis – phagocytosis is defined as the process of engulfment of solid particle material by the cells. Phagocytosis of micro include 3 steps that is recognition and attachment, engulfment, killing and degradation.
Mediators of inflammation
Mediators are large and increasing number of endogenous substances which mediate the process of acute inflammation.
Some common properties of mediators.
- Those are released from the cell or are derived from plasma protein.
- all mediators are released in response to certain stimuli.
- mediators act on different target cells.
- range of action of different mediators are vascular permeability, vasodilation, chemothesis, fever, pain and tissue damage.
- mediators have short life spam after their release.
Mediators divided into two main groups –
- from cell
- vasoactive amines
- Arachidonic acid metabolides
- lysosomal components
- platelet activating factors
- from plasma protein
- the kinin system
- the cloting system
- the fibrinolytic system
- the complete system
So this is the short, simple and easy notes of acute inflammation for pathology.