Acute Inflammation 1 Flashcards
What is acute inflammation?
o Acute inflammation is a fundamental response maintaining integrity of an organism.
o It is a series or protective changes occurring in living tissue as a response to injury.
o It is a dynamic homeostatic response found in higher organisms.
What micro-organisms can cause acute inflammation?
- bacteria
- fungi
- viruses
- parasites
What are the mechanical causes of acute inflammation?
- trauma
- all injuries even sterile
- surgery
What are the chemical causes of acute inflammation?
- upset to pH
- irritation when bile and urine is in inappropriate place
What are the physical- extreme condition causes of acute inflammation?
- heat=sunburn
- cold=frostbite
- ionising radiation
Why does dead tissue cause acute inflammation?
cell necrosis irritates adjacent tissue
What are the cardinal signs of inflammation?
- tumour
- dolor
- rubor
- calor
- loss of function
What is the process of acute inflammation?
o Series of microscopic events
o Localised to affected tissue
o Take place in the microcirculation
o Result in the clinical symptoms and signs of acute inflammation- the cardinal signs.
What is involved in microcirculation?
- capillary beds fed by arterioles and drained by venules
- extracellular space and fluid and fluid and molecules within it
- lymphatic channels and drainage
What do starling forces control?
flow (fluid flux) across membrane
What is involved in dynamic balance?
hydrostatic and colloid pressures, compartments and physical constants
What is pathogenesis in acute inflammation?
o Changes in vessel radius- flow
o Change in the permeability of the vessel wall- exudation
o Movement of neutrophils from the vessel to the extravascular space.
What are the 3 stages in the triple response?
flush, flare and wheal
Describe the process of the triple response.
o Transient arteriolar constriction (few movements, probably protective)
o Local arteriolar dilatation (active hyperaemia)
o Relaxation of vessel smooth muscle (autonomic NS or mediator derived?)
Why is there an increase in blood flow?
o Poiseuille’s law= flow is proportional to radius to the power of 4
o Increased arteriolar radius causes increased local tissue blood flow
o Results in observed redness and heat
o A minute increase in the radius of a vessel will majorly increase the flow if no other factor changes.
Why is there increased permeability of blood vessels?
o It is a localised vascular response that takes place at the microvascular bed.
o There is endothelial leakage, the fluid and proteins are not held in the vessel lumen which causes an imbalance in starling forces.
o Locally produced chemical mediators are involved.
What are the effects of increased permeability?
- Overall there is a net movement of plasma from the capillaries to the extravascular space.
- The process is known as exudation and the fluid leaked is exudate.
- Exudate is a fluid rich in protein, plasma and includes immunoglobulin and fibrinogen
- Fluid loss increases the viscosity which in turn slow rate of flow causing a change in flow characteristic in the vessel
What are the effects of exudation?
- oedema is formed (accumulation of fluid in the extravascular space)
- cause of swelling of tissue
- the swelling causes pain and reduces function
What is normal laminar flow?
- WBC, neutrophils at centre of vessel
- Surrounded by erythrocytes
- Plasma at edge of vessel
What is flow in inflammation?
- loss of normal laminar flow
- red cells aggregate in the centre of the lumen- rouleaux formation
- neutrophils are found near endothelium- margination
What are the phases of emigration of neutrophils?
- margination= neutrophils move to endothelial aspect of lumen
- pavementing= neutrophils adhere to endothelium
- emigration- neutrophils squeeze between endothelial cells. Active process to extravascular tissues
What are some examples of acute inflammation?
- gingivitis
- pleural inflammation
- inflamed appendix
- acute pyelonephritis
- bacterial endocarditis
What is the ideal outcome of acute inflammation?
- inciting agent isolated and destroyed
- macrophages move in from blood and phagocytose debris; the leave
- epithelial surfaces regenerate
- inflammatory exudate filters away
- vascular changes return to normal
- inflammation resolves
What are the benefits of acute inflammation?
- rapid response to non-specific insult
- transient protection of inflamed area (cardinal signs)
- neutrophils destroy organisms and denature antigen for macrophages
- plasma proteins localise process
- resolution and return to normal
What are the outcomes of acute inflammation?
- resolution
- suppuration
- organisation
- chronic inflammation
