PATHOLOGY - Inflammation Flashcards
What are the six key clinical signs of inflammation?
Redness
Heat
Swelling
Pain
Loss of function
Pyrexia
What causes the redness seen with inflammation?
Redness associated with inflammation is due to vasodilation
What causes the heat seen with inflammation?
Heat associated with inflammation is due to vasodilation
What causes swelling associated with inflammation?
Swelling associated with inflammation is due to increased capillary permeability
What causes the pain associated with inflammation?
Pain associated with inflammation is caused by the swelling exerting pressure on free nerve endings
What causes the loss of function associated with inflammation?
Loss of function associated with inflammation is caused by the pain which reduces function, allowing time to heal
What are the three main benefits of inflammation?
Dilutes/inactivates toxins and pathogens
Reduces function to allow time for healing
Increases temperature to induce vasodilation and inhibit the replication of pathogens
What is the disadvantage of inflammation?
Prolonged or excessive inflammation can cause tissue damage
What are the four inflammatory stimuli?
Infectious agents
Microbial toxins
Tissue damage
Foreign bodies
Describe the vascular response to inflammatory stimuli
The vascular response consists of initial transient vasoconstriction followed by vasodilation to increase local blood flow. This is followed by increased vascular permeability to allow for leukocyte recruitment
What causes the initial, transient vasoconstriction seen in the vascular response to inflammatory stimuli?
Endothelial cell contraction
What mediates endothelial cell contraction?
Endothelial cell contraction is mediated by histamine
What prolongs vascular permeability seen in the vascular response to inflammatory stimuli?
Endothelial cell retraction
What mediates endothelial cell retraction?
Endothelial cell retraction is mediated by cytokines
What is leukocyte mediated endothelial cell injury?
Leukocyte mediated endothelial cell injury is seen in the later stages of inflammation where the leukocytes can secrete toxic mediators which can cause damage to the endothelial cells
What are five of the cell-derived inflammatory mediators?
Vasoactive enzymes
Arachidonic acid
Cytokines
Chemokines
Histamine
What are three of the plasma protein inflammatory mediators?
Complement
Coagulation cascade
Kinin system
What is the importance of mast cells in inflammation?
Mast cells are an important source of inflammatory mediators such as histamine, cytokines and chemokines
What is transudate?
Transudate is leaked clear/yellowish fluid containing water, electrolytes and very few proteins
What causes transudate to be leaked?
Transudate is leaked due to conditions which cause an increase in hydrostatic pressure and a decrease in oncotic pressure
What is exudate?
Exudate is leaked fluid containing water, electrolytes, high numbers of proteins and cells (including erythrocytes, neutrophils (pus) and fibrin)
What causes exudate to be leaked?
Exudate is leaked due to the vasodilation and increased vascular permeability caused by the vascular response to inflammation
What are the five steps of leukocyte recruitment?
Margination
Rolling
Adhesion
Transmigration
Chemotaxis
Which stages of leukocyte recruitment are mediated by cytokines and chemokines?
Adhesion, Transmigration and Chemotaxis are mediated by cytokines and chemokines
Describe the margination step of leukocyte recruitment
During vasodilation, the blood flow slows allowing leukocytes to migrate from the central lumen to the periphery, close to the endothelial cell surface
Describe the rolling step of leukocyte recruitment
Leukocytes tumble along the endothelial surface and undergo weak, transient adhesion to the endothelial surface
Describe the adhesion step of leukocyte recruitment
Integrins present on the leukocyte surface firmly adhere to ligands on the surface of the endothelial cells
Describe the transmigration step of leukocyte recruitment
Leukocytes undergo diapedesis
Describe the chemotaxis step of leukocyte recruitment
Chemotaxis the the migration of leukocytes along a chemical gradient to the injury site
What are the three stages of phagocytosis?
Recognition
Engulfment
Killing/degradation
Describe the recognition step of phagocytosis
Phagocytic cells bind to specific cell surface receptors present on pathogens or to opsonins attached to pathogens
Describe the engulfment step of phagocytosis
Pseudopods (cytoplasmic extensions) from the phagocytic cells engulf pathogens and form a phagosome around the pathogen
Describe the killing/degradation step of phagocytosis
A lysosome containing reactive oxygen species binds to the phagosome to form a phagolysosome. The lysosome releases its contents, degrading the pathogen
What are the other two terms used to describe neutrophilic inflammation?
Suppurative inflammation
Purulent inflammation
What are two common stimuli for neutrophilic inflammation?
Infection
Non-infectious tissue damage
What stimulates septic purulent inflammation?
Intracellular bacteria
What defines eosinophilic inflammation?
Eosinophilic inflammation is when more than 10% of the inflammatory cell population is eosinophils
What are five stimuli for eosinophilic inflammation?
Allergy/hypersensitivity
Fungal infection
Parasitic infection
Eosinophilic granuloma
Paraneoplastic disease
What is the difference between granulomatous and pyogranulomatous inflammation?
Granulomatous inflammation is an aggregation of macrophages whereas pyogranulomatous inflammation is an aggregation of macrophages and neutrophils
What is commonly associated with granulomas and pyogranulomas?
Chronic inflammation
What are three common stimuli for lymphocytic inflammation?
Vaccinations
Viral infection
Chronic inflammation
What are four of the causes of chronic inflammation?
Persistent infection
Unresolved acute inflammation
Autoimmunity
Allergy/hypersensitivity
What are four of the morphological signs of chronic inflammation?
Macrophages
Tissue damage
Fibrosis
Angiogenesis
