Inflammatory Response Flashcards
Define Inflammation
- Non-specific, localised reaction to many kinds of insults
- Consists in vascular, metabolic and cellular changes
- Serves to bring defense and healing mechanisms to the site of injury
What are Exogenous Causes of Inflammation?
- Physical Agents
- Mechanic agents: fractures, foreign objects
- Thermal agents: burns, freezing
- Chemical Agents
- Toxic gases, acids, burns
- Biological Agents
- Bacteria, viruses, parasites
What are the Endogenous Causes of Inflammation?
- Circulation disorders
- thrombosis, infarction, hemorrhage
- Enzyme activation
- e.g. acute pancreatitis
- Metabolic products accumulation
- uric acid, urea
What are four signs of inflammation?
- Redness
- local vessel dilatation
- Heat
- local vessel dilatation
- Swelling
- due to influx of plasma proteins and phagocytic cells into the tissue spaces
- Pain
- due to local release of enzymes and increased tissue pressure
What is the general mechanism of inflammation?
- Vasodilation
- Exudation - edema
- Emigration of cells
- Chemotaxis
What is the difference between inflammatory and immune responses?
External trigger > inflammation > immune response or clinical presentation > clinical presentation
Inflammation: non-specific response
Immune Response: specific response
How does vasodilation combat injury?
- Increases delivery, increases temperature and removal of toxins
How does exudate combat injury?
- Delivers immunoglobulin etc., dilutes toxins, delivers fibrinogen, increases lymphatic drainage
How do cells combat injury?
- Removes pathogenic organisms, necrotic debris etc.
How does increased lymphatic drainage combat injury?
- Delivers pathogens to phagocytes and antigens to immune system
How does pain and loss of function combat injury?
- Enforces rest, reduces chance of further traumatic damage
What are the roles of TNF-a and IL-1?
- Responsible for fever and the release of stress hormones (NA, vasopressin, activation of RAAS)
- Responsible for the synthesis of IL-6, IL-8 and IFN-γ
What is the function of pro-inflammatory interleukins?
- either function directly on tissue or work via secondary mediators to activate the coagulation cascade, complement cascade, and the release of nitric oxide, histamine, bradykinin, platelet-activating factor, prostaglandins and leukotrienes
What are the three steps of phagocytosis?
- Recognition and attachment
- Engulfment
- Killing and degradation
What are the steps of leukocyte emigration and chemotaxis?
- Margination, rolling and adhesion to endothelium
- Diapedesis (trans-migration across the endothelium)
- Migration toward chemotactic stimuli from the source of tissue injury
- Phagocytosis
What is emigration?
- Emigration is a process by which leukocytes extend pseudopodia, pass through the capillary walls by amoeboid movement, and migrate into the tissue spaces
- Once they’ve exited the capillary, the leukocytes move through the tissue guided by secreted cytokines and bacterial and cellular debris
What is chemotaxis?
- Process by which leukocytes migrate in response to a chemical signal
What are inflammation outcomes?
- Resolution
- Fibrosis
- Abscess Formation
- Chronic Inflammation
Describe Resolution as an inflammation outcome
- Complete restoration of inflammed tissue back to a normal status
- Inflammatory measures such as vasodilation, chemical production and leukocyte infiltration cease, and damaged parenchymal cells regenerate
- Resolution is the outcome if inflammation is limited or short lived
Describe Fibrosis as an inflammation outcome
- Large amount of tissue destruction, or damage in tissues unable to regenerate
- Fibrous scarring occurs in these areas of damage, forming a scar composed primarily of collagen
- scar won’t contain any specialised structures e.g. parenchymal cells, so functional impairment may occur
Describe Abscess Formation as an inflammation outcome
- A cavity formed which contains pus
What is pus?
- Opaque liquid containing dead WBCs and bacteria with general debris from destroyed cells
Describe Chronic Inflammation as an inflammation outcome in Acute Inflammation
- If the injurious agent persists, chronic inflammation will ensue
- this process, marked by inflammation (lasts many days/months), may lead to formation of a chronic wound
Describe Chronic Inflammation as an inflammation outcome in Chronic Inflammation
- Chronic inflammation is characterised by the dominating presence of macrophages in the injured tissue
- chronic inflammation is almost always accompanied by tissue destruction
