Acute Inflammation Flashcards
(23 cards)
What is inflammation?
- response of vascularized tissues to infection and damaged tissues (cell injury)
- protective response essential for survival
- intimately associated with repair process
What is the purpose of inflammation?
- to bring cells & molecules from the circulation to the sites
- to eliminate agent or cause of cell injury
- to clear necrotic cells & tissues arising from injury
- to initiate repair process
What are the main cells involved in acute inflammation?
Mainly neutrophils
General causes of acute inflammation
- allergic reaction
- frostbite
- chemical irritants
- infection
- burn
- trauma
- cuts, laceration, stabbing
What are the general causes of chronic inflammation?
- cardiovascular disease
- rheumatoid arthritis
- autoimmune disease
- neurological disease
- cancer
- acute inflammation
What is acute inflammation?
- transient and early response to injury
- characterized by release of chemical mediators
- leads to small vessels and leucocytes response
Signs of acute inflammation
- Heat (calor) due to vasodilatation
- Redness (rubor) due to vasodilatation
- Swelling (tumor) due to vascular permeability
- Pain (dolor) due to certain mediators or swelling
- Loss of function (functio laesa) due to pain or swelling
Major components of acute inflammation
Vascular and cellular changes
Vessels: vasodilatation & permeability
Cellular: extravasation & proliferative
Sequential vascular events
- Transient vasoconstriction
- Persistent vasodilatation
- Increase permeability of venules
- Swelling of tissue (edema)
- Reduced blood flow
Examples of mediators causing vasodilation or smooth muscle relaxation
Histamine and nitric oxide
Effects of persistent vasodilatation in acute inflammation
- causes increased blood flow to the area
- causes redness and warmth
- lead to high local hydrostatic pressure which causes transudation of fluid in extracellular space
Why vascular changes of acute inflammation only increases permeability of the venules and not arterioles?
Because tight junction is simpler in venules than arterioles
How does histamine or vasodilatation causes increased permeability of venules in acute inflammation
Histamine or other mediators contract endothelial cells in venules which causes endothelial gaps
How does swelling of tissue occur in vascular changes of acute inflammation?
- Exudation of protein rich fluid.
- Will cause low intravascular osmotic pressure but high osmotic pressure of interstitial fluid (IF)
- This will cause outflow of water and ions - swelling
- Net outflow of fluid from venules exceeds the capacity of lymphatics to remove fluid
- Swelling of tissue (edema, tumor)
What causes reduced blood flow in vascular changes of acute inflammation?
Due to outflow of fluid into the interstitial tissue and increased uptake of fluid by lymphatics
How do vessels become permeable?
- endothelial cells contraction
- direct endothelial injury
- leukocyte-dependent endothelial injury
What are the 2 processes involved in the sequential cellular events in acute inflammation?
- Exudation of leucocytes
2. Phagocytosis
How do leucocytes escape into the interstitial tissue (leucocyte migration)?
- Changes in blood
- Margination and rolling
- Adhesion and transmigration
- Emigration into interstitial tissue
- Role of chemotaxis
Describe the changes in vessel during cellular events of acute inflammation
- Vasodilatation causes stasis.
- There will be disruption of normal axial blood flow
- Plasma loss during exudation also disrupts the flow
- causes neutrophils to come closer to the vessel walls which will cause margination
What facilitates margination in cellular events of acute inflammation?
- plasma lost/exudation
- release of fibrinogen
- RBC rouleoux
- pushed neutrophils to peripheral
- neutrophils come close to the vessel wall
What faciliates rolling and adhesion of leucocytes?
Rolling is facilitated by Selectins
Adhesion is facilitated by ICAM (which help localise leucocytes to site of injury)
Emigration of leucocytes is facilitated by….
PECAM-1 : assist leucocyte to pass through the intercellular junction
Colagenases : help degrade basement membrane so it can pass through
What is the role of chemotaxis in exudation of leucocytes
Chemotactic factor mediate the transmigration of leucocytes to reach the interstitial tissue (site of injury)
Examples of chemotactic factors:
- complement components (CA5)
- arachidonic acid metabolites (LTB4)
- soluble bacterial products (lipoteichoic acid)
- chemokines, cytokines (IL8)
