Acute and Chronic Inflammation Flashcards
List some possible causes of acute inflammation
Microbial infections
Foreign bodies (splinters, dirt, sutures) or trauma (blunt/penetrating)
Hypersensitivity reactions
Physical and chemical agents (thermal injury, irradiation)
Tissue necrosis
List the macroscopic features of acute inflammation
RUBOR - redness (erytherma) CALOR - heat TUMOUR - swelling (odema) DOLOR - pain Loss of function
Describe the changes that occur microscopically in acute inflammation.
- Vasodilation with increased blood flow
- Gaps form in the endothelium as endothelial cells swell and retract
- Exudation: vessels become leaky (to water salts and small proteins)
- Marination & emigration: neutrophils adhere to swollen endothelial cells the migrate through the vessel basement membrane
- Macrophages and lymphocytes migrate in a similar way
What is the action of neutrophils in acute inflammation?
Migrate through the basement membrane, travel to site of injury by chemotaxis.
Phagocytose microorganisms by making contact, recognising and internalising them. Phagosomes then fuse with lysosomes to destroy contents.
Activated neutrophils may also release toxic metabolites or enzymes, causing damage to the host tissue.
What chemical mediators cause vasodilation?
Histamine Prostaglandins C3a C5a Serotonin
What chemical mediators increase vascular permeability?
Histamine
Prostaglandins
Bradykinins
Serotonin
What chemical mediators cause emigration of leukocytes?
Leukotrienes
IL-8
C5a, C3a
What are the systemic consequences of acute inflammation?
Acute phase response = reduced appetite, increased heart rate, altered sleep patterns, changes in plasma concentration of acute phase proteins.
Spread of microorganisms and toxins lead to shock.
Fever produced by endogenous proteins IL-1, TNFa and prostaglandin.
Leukocytosis (high WBCs), IL-1, TNFa produce an accelerated release from bone marrow.
What an happen after an acute inflammation?
- Complete resolution
- Continued acute inflammation with chronic inflammation (abscess)
- Chronic inflammation with fibrous repair
- Death
Why does acute inflammation occur?
Acute inflammation is the response of living tissue to injury and is initiated to limit tissue damage.
How does resolution after acute inflammation occur?
All mediators have short half lives, can be inactivated by degradation/dilution/inhibition.
Gradually all changes reverse and vascular changes stop.
Exudate drains via lymphatics, fibrin degraded by plasmin, neutrophils die.
Damaged tissue may be able to regenerate but if tissue architecture is damaged complete resolution not possible.
Describe some possible complications of acute inflammation.
Swelling can lead to blockage of tubes eg. bile duct, intestine.
Exudate can lead to compression of structures eg. cardiac tamponade, or serositis (inflammation of serous membranes)
Loss of fluid leads to dehydration eg. in burns
Pain and loss of function
Give some clinical examples of acute inflammation
Skin blister
Pericarditis
Abscess
Describe the properties of a skin blister
Caused by heat, sunlight, chemicals.
Pain and profuse exudate (relatively few inflammatory cells so exudate is clear).
Collection of fluid strips off overlying epithelium.
Results in resolution or scarring.
Describe the properties of pericarditis
Inflammation of the serous cavity.
Pericardium becomes inflamed and increases pressure on the heart.
Describe the properties of an abscess
Occurs in solid tissues.
Inflammatory exudate forces tissue apart, liquefactive necrosis in the centre.
May cause high pressure, therefore pain, may cause tissue damage, squash adjacent structures.
What is Hereditary Angio-Odema and how is it treated?
Deficiency of C1 inhibitor which inhibits C1 (complement protein that cleaves C2 and C4 to form C3) and bradykinin.
Uninhibited bradykinin increases permeability of endothelia, causing odema.
Treat with C1 inhibitor infusion or fresh frozen plasma.
What is a1-antitrypsin Deficiency?
a1-antitrypsin inhibits elastase, without inhibition elastase breaks down lung/liver tissue causing emphysema and liver sclerosis.