Acute Inflammation Flashcards
Define acute inflammation
A fundamental response to maintain the integrity of organism
A series of protective changes occurring in living tissue as a response to injury
What are the cardinal signs of inflammation
Rubor - redness Calor - heat Tumor - swelling Dolor - pain Loss of function
What are the causes of acute inflammation
Microorgansims -including bacteria, fungi, viruses, parasites
Mechanical trauma - injury to tissues even in surgery
Chemical - unstable environment e.g. upset pH or bile and urine causing irritation when in inappropriate places
Physical - extreme conditions e.g. heat, cold, ionising radiation
Dead tissue - cell necrosis irritates adjacent tissue
Hypersensitivity - causes several classes of reaction
What changes occur in acute inflammation
Changes in:
Vessel radius (flow)
The permeability of the vessel wall (exudation)
And movement of neutrophils from the vessel to the extravascular space
What are the benefits of acute inflammation
A rapid response to non-specific insult
Cardinal signs and loss of function (allowing transient protection of the inflamed area)
The neutrophils destroy organisms and denature antigens for macrophages
Plasma proteins localise the process
It can be resolved and return to normal
What is acute inflammation
Series of microscopic events occur which are localised to the affected tissue
They take place in the microcirculation
Result in the clinical symptoms and signs of acute inflammation
What happens in the process of exudation
There is a net movement of plasma from capillaries to extravascular space causing fluid to be leaked which is exudate
Exudate fluid is rich in protein and plasma and it includes Ig and fibrinogen
What can exudation cause
Oedema - the accumulation of fluid in the extravascular space
Presents as the swelling of tissue in acute inflammation which cause pain and reduce function
How are inflammation at various anatomical positions named
“Structure”-itis
e.g. peritoneal cavity inflammation is peritonitis, meninges inflammation is meningitis, appendix inflammation is appendicitis.
What is an exemption to the rule of how inflammation is named
Lungs which is known as pneumonia
Pleural cavity is known as pleurisy
What is the role of neutrophils
They are mobile phagocytes Recognise foreign antigen Adhere to organism Release granule contents Phagocytose and destroy foreign antigen
What do the granules in neutrophils contain
Oxidants (e.g. H202)
Enzymes
What happens to the neutrophil when the granule contents are released
They die
What is produced from a neutrophil
A ‘soup’ of fluid
Bits of cell
Organisms
Endogenous proteins
This is known as pus
What is fibrinogen
A coagulation factor which forms fibrin and colts exutade
It localises inflammatroy processes
What is the role of immunoglobulins in plasma
They are specific for the antigen
Involved in the humoural immune response
Name the type of mediators in acute inflammation
Molecules on endothelial cell surface membrane,
Molecules released from cells
Molecules in the plasma
What are the collective effects of mediators
Vasodilatation Increased permeability Neutrophil adhesion Chemotaxis Itch and pain
What are cell surface mediatiors
Adhesion molecules which appear on endothelial cells
Give example of cell surface mediatiors
ICAM-1 which help neutrophils stick
P-selectin which interact with the neutrophil surface
Give examples of the molecules released from cells
Histamine
5-hydroxytryptamine (serotonin)
Prostgladins (arachidonic acid metabolites via cyclo-oxygenase pathway)
Leukotrienes (arachidonic acid metabolites via lipoxygenase pathway
Omega-3 polyunsaturated fatty acids
Platelet-activating factor (PAF)
Cytokines and chemokines (e.g. TNFα, IL-1)
Nitric oxide (NO)
Oxygen free radicals (H2O2, OH-, O2-)
Describe histamine
Preformed in mast cells beside vessels, platelets and basophils
Released due to local injury which cause IgE mediated reactions
Cause vasodilatation
Increase permeability
Act via H1 receptors on endothelial cells
Describe 5-hydroxytryptamine (serotine)
Preformed in platelets
Released when platelets degranulate in coagulation causing vasoconstriction
Describe prostglandins (arachidonic acid metabolites via cyclo-oxygenase pathway)
Formed from many cells including endothelium and leukocytes
Many of the cells promote histamine effects and inhibit inflammatory cells
Give an example of a prostglandins and its actions
Thromboxane A2
Promotes platelet aggregation and vasoconstriction
Opposite to PGD2 and PGE2
PGE determines the effectiveness of non-steroidal anti-inflammatory drugs.
Give examples of leukotrines
Neutrophils
They are vasoactive so have a dynamic effect on vessels to increase permeability as well as constrict smooth muscle
What are prostglandins
Arachidonic acid metabolites from the cyclo-oxygenase pathway
What are leukotrines
Arachidonic acid metabolites from the lipoxygenase pathway
What do omega-3 polyunsaturated fatty acids do
Decrease the synthesis of arachidonic acid that is derived from inflammatory mediators