Acute inflammation Flashcards
What are the cardinal signs of inflammation?
Rubor- redness
Calor- heat
Tumour- swelling
Dolor- pain
What microorganisms can cause inflammation?
Bacteria, fungi, viruses, parasites
What are the causes of inflammation?
Microorganisms Mechanical (trauma) Chemical Physical (extreme conditions) Dead tissue Hypersensitivity
What is present in the microcirculation?
Capillary beds and extracellular space and fluid within it
Lymphatic channels and drainage
What is the pathogenesis of acute inflammation?
Changes in vessel radius
Change in permeability of vessel wall
Movement of neutrophils to extracellular space
What is the triple response?
Flush- transient arteriolar constriction
Flare- local arteriolar dilation
Wheal- relaxation of vessel smooth muscle
What effect does increasing the vessel radius have an flow?
Increases flow by power of 4
What are the effects of increased vessel permeability?
Net movement of plasma from capillaries to extracellular space
Causes oedema and increased viscosity of blood
What are the effects of increased blood viscosity?
Causes stasis and a change in flow pattern
What are the phases of emigration of neutrophils?
Margination
Pavementing
Emigration
How is acute inflammation resolved?
Inciting agent isolated and destroyed Macrophages move in and phagocytose debris Epithelial surfaces regenerate Inflammatory exudate filtered away Vascular changes return to normal
What are the benefits of acute inflammation?
Rapid response to non-specific stimuli
Transient protection of inflamed area
Localised process
What are the outcomes of acute inflammation?
Resolution
Suppuration
Organisation
Chronic inflammation
What is chemotaxis?
Movement of neutrophils up a concentration gradient
How to neutrophils destroy pathogens?
Enzymes destroy a specific part of the pathogen
Oxygen free radicals pick up particular molecules and destroy them
What are the consequences of neutrophil action?
Produce pus
Progress inflammation, if necessary
What plasma proteins are involved in acute inflammation?
Fibrinogen
Immunoglobulins
What is the role of fibrinogen in acute inflammation?
Forms fibrin
Clots exudate
Localised inflammatory process
What is the role of immunoglobulin in acute inflammation?
Antigen specific
Part of humeral immune response
What are the collective effects of mediators?
Vasodilation Increased permeability of vessel walls Neutrophil adhesion Promote chemotaxis Itch and pain
What is P selectin?
Secreted from endothelial cells and sits on surface, acting as glue to stick to neutrophils
What molecules are released from cells during acute inflammation?
Histamine Seratonin Omega 3 polyunsaturated fatty acids Platelet activating factor Cytokines and chemokines Nitric oxide Oxygen free radicals
What cell is histamine released from and what does it do?
Mast cells
Vasodilation and increased permeability
What cell is serotonin released from and what is its function?
When platelets degranulate in coagulation
Causes vasoconstriction
What is the function of omega 3 polyunsaturated fatty acids?
Decrease synthesis of some other inflammatory mediators
What cell type is platelet activating factor released from and what is its function?
Cell membranes of activated inflammatory cells
Reduces permeability by increased platelet degranulation
What cells are cytokines and chemokine released from and what is their function?
Macrophages, lymphocytes and endothelium
Attract inflammatory cells
What is the function of nitric acids in acute inflammation?
Regu;ate leukocyte recruitment and cause smooth muscle contraction
What cell are oxygen free radicals released from and what is their function?
Neutrophils during phagocytosis
Amplify other mediator effects
What are the 4 enzyme cascades?
Blood coagulation
Fibrinolysis
Kinin
Complement cascade
What is the purpose of the blood coagulation pathway and how does it work?
Form clots in exudate
Converting fibrinogen to fibrin
What is the purpose of fibrinolysis?
Break down fibrin to maintain blood supply
What is the purpose of the kinin pathway?
Triggers nerves causing pain
Build upon stimulation from peripheral nerves
What is the purpose of the complement cascade and how does it work?
Tie inflammation with the immune system
Stimulates increased permeability, chemotaxis, phagocytosis and cell breakdown
What are the immediate systemic effects of inflammation?
Pyrexia
Feel unwell
Neutrophilia- increased white cell count
What are the longer term effects of inflammation?
Lymphodenopathy- regional lymph node enlargement
Weight loss
Anaemia
What is suppuration?
Pus formation
What is the structure and function of the pyogenic membrane?
Formed by fibrin
Walls off pus to prevent spread
What is an abscess?
Collection of pus under pressure
Can be a single macule or multiloculated
What is pyaemia?
When pus discharges into the bloodstream
What is organisation?
Healing and repair leading to fibrosis and formation of a scar
What is granulation tissue and what is it formed from?
‘Universal patch’
Ner capillaries, fibroblasts and collagen, macrophages
What is dissemination?
Spread of acute inflammation into bloodstream
What is bacteraemia?
Bacteria in blood
What is septicaemia?
Growth of bacteria in blood
What is toxaemia?
Toxic products of bacteria in blood
What is the cardiac output?
Volume of blood the heart pumps in 1 minute
How is cardiac output calculated?
Stroke volume x heart rate
What is stroke volume?
The volume of blood the heart pumps with each beat
How is blood pressure calculated?
Cardiac output x systemic vascular resistance
What is the systemic vascular resistance?
Inbuilt pressure surrounding vessels
What is an effect of systemic infection?
Shock
What is shock?
Inability to perfuse tissues due to a low BP
What are the clinical signs of early septic shock?
Peripheral vasodilation Tachycardia Hypotension Pyrexia Haemorrhage skin rash
What does the systemic release of chemical mediators cause?
Vasodilation, therefore loss of systemic vascular resistance
Heart rate increases to compensate
What does bacterial endotoxin release cause?
Pyrexia
Activates coagulation causing haemorrhage skin rash
