3 - Acute and Chronic Inflammation (Exam 1) Flashcards
What is inflammation?
A protective response intended to eliminate the initial cause of cell injury as well as any products of the injury (necrotic cells or tissue).
What is 1 good/necessary aspect of inflammation?
To destroy and/or neutralize harmful agents such as:
Toxins
Microbes
What is 1 negative aspect of inflammation?
An overreactive response
What are 4 examples of overreactive inflammatory responses?
- Excessive scar tissue formation’
- Anaphylaxis
- Arthritis
- Atherosclerosis
Give a brief overview of inflammation (4 steps)
- Insult to tissue
- Release of chemical mediators
- Mediator amplification of the initial inflammatory response
- Termination of the inflammatory response
What are the 2 patterns of inflammation?
- Acute
- Chronic
These two patterns can overlap in mechanism and appearance
What is acute inflammation?
Immediate and early response to injury
Brought on by release of local chemical mediators
What are 5 types of vascular changes?
- Arteriolar vasodilation
- Contraction of endothelial cells
- Retraction of endothelial cells
- Leukocyte dependent injury
- New blood vessel leakage
Give a brief overview of arteriolar vasodilation
- Causes erythema (redness)
- Increases permeability of vasculature
- Increases viscosity of the blood
- Rate of blood flow slows (stasis)
- Leukocytes move to the margin of the vessel
List 1 potential cause of increased vascular permeability
Injury to the endothelial lining (endothelial cell death, followed by necrosis and detachment)
Contraction of endothelial cells is initiated by what 3 mediators?
- Bradykinin
- Leukotrienes
- Histamines
Give a brief overview of contraction of endothelial cells
Leads to intracellular gaps
Usually occurs in venules
Is reversible and transient
How are endothelial cell contraction and retraction different?
Endothelial cell retraction takes longer to occur and also lasts longer.
What causes a leukocyte dependent injury to occur?
Accumulation of leukocytes
What is angiogenesis?
Formation of new blood vessels
For how long do new blood vessels leak?
Until the endothelial lining is complete
What causes angiogenesis?
The release of growth factor
What are cellular events?
The movement of leukocytes out of the circulation and into the interstitial space as induced by chemical mediators.
What are 6 types of cellular events?
- Rolling and Margination
- Adhesion
- Transmigration
- Chemotaxis and Activation
- Phagocytosis and Degranulation
What do adhesion and transmigration have in common?
- Both processes involve mediating molecules on cell surfaces
- Integrins on leukocytes, selectins on endothelial cells
Where does rolling and margination occur?
Post-capillary venules
What is rolling?
Rolling of the leukocytes along vessel walls due to loose and transient adhesion between the leukocytes and endothelial cells
What causes margination?
The small RBCs tend to move through the middle of the vessel leading to the leukocytes traveling against the vessel wall
This increases viscosity of the blood
What is adhesion?
Leukocytes firmly adhere to endothelial cells
What is transmigration?
Leukocytes squeeze between cells and intercellular junctions
They cross basement membranes by degrading them with collagenases
Moving into interstitial space is called diapedesis
For transmigration, different leukocytes take different amount of time to move in different situations. What type of leukocytes moves in which situation and about how long does each take?
Neutrophils - move in acute situations - 6 to 24 hours
Monocytes - move in chronic situation - >24 hours
What is chemotaxis?
Movement of WBCs toward site of injury due to chemical attraction
What are 3 chemotaxis agents?
- Soluble bacterial products
- Leukotrienes
- Cytokines
How do cells move by chemotaxis?
Binding of chemotactic molecule to receptors triggers a reaction to cause movement by pseudopods.
What are the 3 steps of phagocytosis and degranulation?
- Recognition and attachment of leukocyte and inflammatory agent
- Engulfment and formation of phagocytic vacuole
- Killing and digestion of ingested material
What are 3 general principles of chemical mediators of acute inflammation?
- Can be produced by cells at the site of the injury
- Can be circulating in the plasma
- Some may work as enzymes
What are 3 types of chemical mediators?
- Vasoactive amines
- Neuropeptides
- Plasma proteases
What are two examples of vasoactive amines and what is their function?
- Histamine
- Seratonin
Both increase vascular permeability due to endothelial contraction and cause vasodilation
What are neuropeptides?
Small proteins released from nerve fibers that have similar effects to vasoactive amines
The Hageman factor becomes activated by exposure to what 3 things?
- Collagen
- Basement membrane
- Activated platelets
What 3 things are linked by the initial activation of Hageman factor?
- Kinins
- The clotting cascade
- The compliment cascade
Bradykinin is formed as a result of the activation of what system?
The kinin system
What are 3 functions of Bradykinin?
- Increase vascular permeability
- Arteriolar dilation
- Bronchial smooth muscle dilation
What does activation of the clotting system result in?
The activation of Thrombin
What does thrombin cause?
The conversion of soluble fibrinogen to insoluble fibrin.
What is the compliment system?
A cascade of proteins in the plasma that play a big role in immunity and inflammation.
What are three examples of eicosanoids?
- Leukotrienes
- Prostaglandins
- Lipoxins
What 4 steps of inflammation can eicosanoids mediate?
- Vasodilation
- Vasoconstriction
- Platelet aggregation
- Chemotaxis
What are cytokines?
Polypeptide products that are released from activated lymphocytes and macrophages that function to regulate the function of other cells.
What are chemokines?
Small chain polypeptides that act as activators and chemo-attractants of leukocytes
What are 2 outcomes of acute inflammation?
- Resolution
2. Scarring or Fibrosis
What are some characteristics of resolution of acute inflammation?
- Short lived
- Minimal damage
- Recovery/ replacement of damaged cells
- Removal of necrotic debris/ clearance of edema
- Little loss of function
What are some characteristics of scarring/ fibrosis resulting from acute inflammation?
- Substantial damage, regeneration not possible
- Fibrinous exudates collect and are not removed
- Increase in fibroblast activity
- Abscess formation (usually results from microbes)
