Acute Inflammation Flashcards
Define acute inflammation
Protective changes as a response to injury in order to maintain the integrity of a higher organism
List the cardinal signs of acute inflammation
Rubor (redness) Calor (heat) Tumor (swelling) Dolor (pain) Loss of function
Give the 6 causes of acute inflammation
Micro-organism (infection) Mechanical (trauma) Chemical (pH) Physical (heat/cold) Necrosis Hypersensitivity
Name the three processes which give rise to acute inflammation
Vessel radius changes
Permeability changes
Neutrophil movement
Describe how changes in vessel radius give rise to acute inflammation
Increased flow of blood is caused by successive arteriolar constriction/dilation followed by smooth muscle relaxation
(Poiseulle’s Law)
Describe how changes in permeability give rise to acute inflammation
Swelling is caused by net movement of material (plasma/protein/fibrinogen/immunoglobulin) out of capillaries
Causes an increase in blood viscosity leading to stasis (decreased/low flow rate)
Describe how neutrophil movement gives rise to acute inflammation
Loss of normal laminar flow is caused by RBCs gathering in the centre of the blood vessels and neutrophils gathering at the edges near the endothelium
Neutrophil;
Margination (movement to edges)
Pavementing (adherence to endothelium)
Emigration (movement from endothelium to extravascular tissues)
How is acute inflammation resolved?
Isolation and destruction of inciting agent Phagocytosis of debris by macrophages Epithelial regeneration Exudate filters away Normalisation of vascular changes
What is meant by the margination of neutrophils?
Movement to edges of blood vessels
What is meant by the pavementing of neutrophils?
Adherence to endothelium
What is meant by the emigration of neutrophils?
Movement from endothelium to extravascular tissues
Give three benefits of acute inflammation
Rapid response (due to cardinal signs - protection)
Neutrophil action
Localisation (by plasma proteins)
Give the possible outcomes of acute infection?
Resolution
Suppuration (pus formation)
Organisation
Development of chronic inflammation
What suffix is given to conditions of acute inflammation and give some examples
- it is
e. g. meningitis, pancreatitis, appendicitis
What is the role of the neutrophil in acute inflammation?
Chemotaxis
Adherence
Release of granule contents
Phagocytosis and destruction of foreign antigens
What are the contents of neutrophil granules?
Oxidants and enzymes
What happens to neutrophils when they release the contents of their granules?
They die and contribute toward pus formation (suppuration)
Name two plasma proteins involved in acute inflammation
Fibrinogen
Immunoglobulins
What is the function of fibrinogen in acute inflammation?
Parts cleaved off to form fibrin
Polymerisation to form clots
Hems in the exudate to localise the process
What are mediators of acute inflammation?
- on endothelial surface
- released from cells into plasma
What are the functions of mediators of acute inflammation?
Vasodilation Increased permeability Neutrophil adhesion Chemotaxis Itch & Pain
- Gradation/balance exists - not just an on/off mechanism; alternating actions depend on timing/circumstance
- Favour or inhibit the inflammation, depending on bodily need
Give some example of mediators of acute inflammation and their functions
Histamine - vasodilation and increased permeability
Serotonin & Prostaglandins - vasoconstriction
Leukotrienes - increased permeability and smooth muscle constriction
Hydrogen peroxide - amplification of other mediators
What is the difference between bacteraemia and septicaemia?
The presence of bacteria in the blood versus their growth
What is septic shock an example of?
Systemic effect of acute inflammation
Give the symptoms of septic shock?
- peripheral vasodilation
- tachycardia
- hypotension
- pyrexia
- haemorrhagic skin rash
What causes the tachycardia associated with septic shock?
During vasodilation, systemic vascular resistance decreases
Cardiac output must adjust to the changes in SVR in order to regulate blood pressure
BP = CO X SVR
When CO can no longer cope, the hypotension comes in
How is pus organised in acute inflammation?
In an abscess surrounded by a pyogenic membrane
What is pyaemia?
Pus in the bloodstream
What is empyema?
Pus in a pre-existing hollow cavity
Describe organisation as a possible outcome of acute inflammation?
Formation of granulation tissue for healing and repair
Leads to fibrosis and scar tissue formation
Made from;
new capillaries/fibroblasts/collagen/macrophages
