Acute Inflammation I Flashcards
What is the definition of inflammation and what does it involve?
Local reaction of vascularized tissue to injury.
Must be an injury, host needs a vascular system to respond, and is a local reaction
What are the time intervals for the 3 types of inflammation?
Acute - 0-2 days
Subacute - 2-14 days
Chronic - 14 days
Classify the types of inflammation based on the cells
Acute - neutrophils or eosinophils (allergy)
Subacute - neutrophils, monocytes, lymphocytes, plasma cells, fibroblastic elements, angioblastic elements
Chronic - mononuclear cells like monocytes, lymphocytes, plasma cells, macrophages, granuloma cells (epithelioid cells and giant cells)
What do eosinophils do?
Predominant inflammatory cells in allergic reactions and parasitic infestations
What are the inflammatory cells involved?
Eosinophils
Basophils
Fibroblasts - repair/scarring
Mast cells
Platelets
What are the plasma-derived molecular systems involved in inflammation?
Immune system - Ab, C3, C5 fragments
Kinin system - Bradykinin
Clotting system - thrombin
Fibrinolytic system - plasmin
Acute phase proteins - CRP, ceruloplasmin, haptoglobin
What are the tissue-derived molecular systems involved in inflammation?
Vasoactive amines - histamine, serotonin
Acidic lipids - prostaglandins, leukotrienes, lipoxins
Cytokines - IL-1, TNF
Chemokines - IL-8, MCP-1, MP-1alpha, lymphotactin
Others - PAF, nitric oxide, free radicals, lysosomal enzymes
What is the purpose of inflammation?
Protective response meant to get rid of:
Initial cause of injury - microbes, toxins
Consequences of such injury - necrotic cells and tissue
When is inflammation not good?
Inflammatory reactions underlie common chronic diseases
Uncontrolled inflammatory response can lead to life-threatening hypersensitivity reactions
Repair can produce constrictive scarring and limb immobilization
What are the 6 cardinal signs of inflammation?
- Heat - increased blood flow to site
- Redness - increased blood flow
- Swelling - accumulation of water and cells
- Pain - pressure of fluid and effect of mediators
- Loss of function
- Systemic changes - release of humoral factors
What are the 2 characteristics of acute inflammation?
2 days
Neutrophils and macrophages (later stage)
What are the causes of inflammation?
- Infection
- Trauma
- Physical injury - thermal extremities or ionizing radiation
- Chemical injury
- Immunologic injury
- Tissue necrosis
What are the 4 morphological patterns in acute inflammation?
Serous
Fibrinous
Suppurative (purulent)
Ulceration
What are the characteristics of serous patterns in acute inflammation?
Serous is outpouring of watery, relatively protein-poor fluid (effusion)
Derives from serum or mesothelial cell secretions (peritoneal, pleural, or pericardial cavities)
Examples: skin blisters from burn or viral infection
What are characteristics of fibrinous patterns in acute inflammation?
Seen in more severe injury since more protein loss
Increased vascular permeability allows leakage of larger molecules (fibrinogen), which becomes insoluble fibrin extravascularly
Characteristic of inflammation of body cavities
May resolve over time (resolution)
If fibrin not removed, ingrowth of fibroblasts and blood vessels might happen
What is the process of organization with fibrinous inflammation?
If fibrin is not removed, ingrowth of fibroblasts and blood vessels can occur
What are the characteristics of suppurative (purulent) patterns in acute inflammation?
Mainfested by large amounts of pus
Certain organisms more likely to cause this like pyrogenic bacteria
Can lead to abscess
May become walled off over time by fibroblastic proliferation (chronic inflammation and repair)
What does pus contain?
Neutrophils, necrotic cells, and edema fluid
In many cases it can contain microbes
What is an abscess?
Focal collection of pus, central necrotic region surrounded by layer of preserved neutrophils
What are the characteristics of ulceration patterns in acute infammation?
Local defect, excavation produced by sloughing of inflammatory necrotic tissue
Can only occur on or near a surface - skin and mucosa
Most common in mucosa of mouth, GI tract, GU tract, and lower extremities
Can be acute or chronic
What are the morphological patterns of acute and chronic ulceration?
Acute - neutrophils and vascular dilation in margins
Chronic - first as acute, but over time, fibroblastic proliferation in base of ulcer with chronic inflammatory cells and scarring
What are the outcomes of acute inflammation?
- Resolution - complete tissue restoration
- Healing by scarring - after substantial tissue destruction and occurs in tissues that can not regenerate (e.g. brain)
- Abscess - infections with pyogenic organisms
- Progress to chronic inflammation
What are the 3 key events of acute inflammation?
- Increase in blood flow from alterations in vascular caliber
- Structural changes in the microvasculature that allow plasma proteins and leukocytes to leave circulation
- Emigration of leukocytes from microcirculation, their accumulation in the focus of injury, and their activation to eliminate the offending agent
What are the hemodynamic changes in vasculature that occur with inflammation?
Vasoconstriction first of arterioles that is immediate and transient
Vasodilation of arterioles and venules and precapillary sphincters open. Results in increased capillary blood flow
Increased permeability - takes place at level of capillaries and postcapillary venules as endothelial cells contract thus widerning their intercellular junctions
Leakage of fluid to interstitial space - edema
Decreased absorption of fluid from interstitial space
Stasis of circulation resulting in increased blood viscosity
