What is inflammation, the cause and the types
Inflammation:
- Response of vascularised tissues to infections and tissue damage
- Brings cells and molecules of host defence from circulation to sites where they are needed, to eliminate offending agents
Types:
- Acute (seconds to 2-3 days)
- Sub-Acute (2 weeks)
- Chronic (weeks to months)
Cause:
- Complex response to injurious agents that consist of vascular response, cellular reaction and systemic reaction
What are the main characteristic features of early acute inflammation
- Immediate / rapid and early defensive response in host tissue to injury
- Non-specific
- Exudate: Inflammatory extravascular fluid / infiltrate, plasma liquid, plasma proteins, WBC, RBC, cellular debris
- Causes changes in microcirculation
- Exudation of fluid
- Emigration of leukocytes
What are the 5 cardinal signs of acute inflammation
- Heat: Vasodilation
- Redness: Increased vascular permeability
- Swelling: Leukocyte extravasation / release of chemicals
- Pain: Leukocyte activation
- Loss of function: Endothelial damage
What is vasodilation (acute inflammation)
- Arteriolar Vasodilation
- Increased blood flow
- Erythema
- Leads to heat loss across epidermis
What is increased vascular permeability (acute inflammation)
- Endothelial cells involved in exudation of protein rich fluid into interstitium
- Expansion of capillary bed facilitates this movement
- Edema: Marked outflow of fluid and accumulation in interstitial tissue
- Blood: Increased viscosity, vascular stasis which impedes outflow
What are the different classifications of fluids
- Transudate: Fluid leakage due to increased hydrostatic / decreased osmotic pressure, ultra filtrate of plasma with little protein and few or no cells
- Exudate: Extravascular fluid collection, rich in protein and cells, in inflammation, vascular permeability increases
- Edema: Excess extravascular fluid in interstitial space, either transudate or exudate
- Pus: Made up of neutrophils, necrotic cells and edema fluid
- Serous: Transudate with mainly edema fluid and cells
- Serosanguinous: Effusion containing RBC
What is leukocyte extravasation (acute inflammation)
- Delivers delivers leukocytes from blood to site of injury
- Involves adhesion receptor (selectins, Ig family, integrins and mucin-like glycoproteins)
- Process: Margination, transmigration and migration
What is the process of leukocyte extravasation
Margination:
- Leukocytes adhere to endothelial cells of BV due to CAMs
- Selectins teacher neutrophils to endothelium, begin rolling
- Tighter binding through ICAMs through integrins
Transmigration:
- Leukocytes move across the endothelium
Migration:
- Movement of leukocytes into interstitial tissue
- Movement towards chemotactic stimuli
- Phagocytosis of microbes
- Leukocyte induced acute cytokine immediate response / induced endothelial expression of receptors
What is leukocyte activation
- Recognition of microbes and mediators via phagocytic receptors
- Lead to phagocytosis and production of ROS lysosomal enzymes
- Lead to leukocyte activation and killing of microbes
What is the wheal and flare response
- Triple Response: Histamine, saline and allergens
- Reddening: Vasodilation
- Flare: Red halo, hyperaemia
- Wheal: Swelling, fluid accumulation
What are inducers of acute inflammation
- Infections
- Trauma
- Physical and chemical agents
- Foreign bodies
- Tissue necrosis
- Hypersensitivity reactions
- Environmental / non-selfsubstances
What are systemic clinical signs of acute inflammation
- Fever: Entry of pyrogens and release of prostaglandins
- WBC Count: BM release / production, increased neutrophils, lymphocytes, neutropenia and high WBC
- Plasma Proteins: Changes in plasma protein levels
What is the outcome of acute inflammation
- Complete resolution
- Abscess formation
- Fibrosis (substantial tissue destruction, little regeneration, abundant fibrin exudation)
- Progression to chronic inflammation
List the 4 morphological patterns of acute inflammation
- Serous: Accumulation of excessive clear watery fluid, skin peritoneal, pleural / pericardial cavities, exudate w low plasma protein / cell content
- Fibrinous: Increased fibrin / fibrinogen in vessel wall / extracellular spaces (pleura, pericardium), exudate w high plasma protein
- Catarrhal: Inflammation of mucous membranes, airways / cavities, enlargement of epithelial cells, exudate of mucous / WBC
- Purulent / Suppurative: Bacteria, pus / purulent w neutrophils, necrotic cells and edema
What are examples / nomenclature of acute inflammation
- Appendicitis: Inflammation of the appendix
- Cellulitis: Inflammation of skin
- Meningitis: Inflammation of brain
- Pneumonitis: Inflammation of lungs
- Nephritis: Inflammation of kidney
- Myocarditis: Inflammatory cardiomyopathy, inflammation of heart muscle
What are abcesses’
- Localised collections of purulent inflammatory tissue
- Defence reaction to bacteria
- Abscess seals infected tissue from adjacent healthy cells
- Central Region: Mass of necrotic leukocytes / tissue with zone of neutrophils
- Outer Region: Vascular dilation, parenchymal / fibroblastic proliferation
- Over Time: Replaced by connective tissue
- Exudative purulent localised inflammation
What is and the causes of chronic inflammation
- Response of prolonged duration (weeks or months)
- Inflammation, tissue injury, and attempts at repair coexist
- Sum of responses mounted by tissue against a persistent injurious agent / aggressive stimuli
- Persistent infections / long lasting infections
List the four main causes of chronic inflammation
- Persistant infections
- Prolonged exposure
- Autoimmunity
- Non-resolution
What are persistent infections and examples (chronic inflammation)
- Persistent infections by microorganisms that are difficult to eradicate
- Examples: Mycobacteria and certain viruses, fungi, and parasites
Tuberculosis: - Systemic infectious disease
- Caused by mycobacterium tuberculosis
- Varying manifestations, creates tuberculous granuloma (caseation of necrosis)
- Treated with antibiotics
What is prolonged exposure and examples (chronic inflammation)
- Prolonged exposure to potentially toxic agents (exogenous or endogenous)
Silica: - Exogenous particulate
- Causes silicosis when inhaled for prolonged periods - Inflammatory lung disease
Hyperlipidaemia: - Excessive production and tissue deposition of endogenous cholesterol, triglycerides and other fats
- Causing atherosclerosis of arterial wall
What is autoimmunity (chronic inflammation)
- Autoimmune diseases
- Malfunction in immune system
- Components of patient’s own body get attacked
- Chronic tissue damage and inflammation
Multiple Sclerosis: - Lesions (early / chronic)
- Cause inflammation / demyelination
- Contain activated T / B cells, macrophages and pro-inflammatory cytokines
- Early: Mononuclear inflammatory cells
- Chronic: Complete demyelination severe astrogliosis very little inflammation
Allergies: - Type 1 hypersensitivity
- Vasodilation and nerve irritation
What is non-resolution (chronic inflammation)
- Following acute inflammation
- Chronic Leg Ulcer: Break in skin of leg allows air and bacteria to invade underlying tissue, leads to poor circulation and venous / arterial disease
What is an example of specific chronic inflammation
- Granulomatous inflammation
Granuloma: - Nodular activated macrophages (0.5-2mm) surrounding a central core
- Surrounded by a rim of lymphocytes, macrophages and some fibrosis
What are the type of granulomas in the body
Foreign Body Granuloma:
- Particles too large to be phagocytosed
- Material is inert (doesn’t provoke immune response)
- Endo: Keratin, cholesterol
- Exo: Splinter, parasite
Immune Granuloma:
- Insoluble particles
- Capable of inducing cell mediate immune response
- Non-degradable antigens
Unknown Aetiology Granuloma:
- Crohn’s disease
- Portion of GIT
- Inflammation, clusters of neutrophils with crypts
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Histology10
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Cells and Tissues14
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Cell Injury (Reversible and Irreversible)17
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Cell Death (Apoptosis and Necrosis)17
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Disorders of Cell Growth31
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Inflammation28
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Healing and Repair28
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CVS Pathology36
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CNS Pathology31
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Haemodynamic Disorders17
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Pulmonary Pathology26
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Renal Pathology21
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Gastrointestinal Pathology24
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Bone and Joint Pathology0
