Inflammation Flashcards
Types of Inflammation by appearance (Macroscopic appearance)
-Haemorrhagic inflammation
Hemorrhagic inflammation indicates severe vascular injury or depletion of coagulation factors
EXAMPLE: acute pancreatitis
Causes of Acute Inflammation
- Chemical Agents (irritant and/or corrosive)
Corrosive chemicals (acids, alkalis, oxidizing agents) provoke inflammation through gross tissue damage.
3 Patterns for Increased Leakage from Vessels
- An immediate response that is transient, lasts for 30-60 minutes, and is mediated by HISTAMINE acting on endothelium.
- A delayed response that starts 2-3 hours after injury and lasts for up to 8 hours. This is mediated by factors synthesized by local cells (e.g. BRADYKININ); factors derived from complement; and factors released from dead neutrophils in the exudate.
- An immediate response that is prolonged for over 24 hours and is seen if there has been DIRECT NECROSIS of endothelium.
Chemical Mediators
Chemical Mediators (Lysosomal Compounds)
EFFECTS: Increase vascular permeability, increase proteases which may activate complement.
CELLS: Neutrophils (and include cationic proteins)
Types of Inflammation by appearance (Macroscopic appearance)
-Fibrinous inflammation
When the inflammatory exudate contains plentiful fibrinogen (huge molecule in plasma), this polymerizes into a thick fibrin coating
EXAMPLE: acute pericarditis
Chemical Mediators
Chemical Mediators (Lymphokines)
EFFECTS: Chemotaxis or vasoactive
CELLS: Lymphocytes
Phases of Leukocyte (neutrophil) Journey in Inflammation
- Margination & Adhesion - move to edge of wall and attach -Pavementing
- Migration toward chemotaxic stimulus - squeeze through wall and move toward enemy.
- Phagocytosis & Intracellular degradation
*If tissue damage is extensive, neutrophils from bone marrow will be released.
Abscess (and removal of it)
Once pus begins to accumulate in a tissue, it becomes surrounded by a ‘pyogenic membrane’ (walling it off with this membrane to keep it contained) and such a collection is called an abscess (any accumulation of pus in tissue).
Since bacteria within the abscess cavity are relatively inaccessible to antibodies and to antibiotic drugs surgical incision and drainage is necessary to eliminate the abscess.
Steps involved in Acute Inflammatory Response (BIG PICTURE)
- Vasoconstriction (initial transient phase)
- -Vasodilation - opening of arterioles resulting in active hyperemia.
- -Slowing of circulation due to increased blood viscosity related to escape of plasma into tissues
- -Endothelial cells swell and partially retract leaving gaps.
- -Vessels become leaky and leakage forms exudation (fibrinogen leaks out..?)
- -Circulating neutrophils adhere to endothelial cells (margination) then actively migrate through basement membrane (emigration), passing into area of tissue damage.
- -Later, blood monocytes (macrophages) and lymphocytes migrate in similar way.
Chemical Mediators
Chemical Mediators (Leukotrienes)
EFFECTS: Vasocontriction
CELLS: Neutrophils (mainly)
Synthesized from arachidonic acid, especially in neutrophils, and appear to have vasoactive properties.
Chemical Mediators of Acute Inflammation: Plasma Factors
The plasma contains four enzymatic cascade systems:
- Complement system
- Kinin system
- Coagulation system
- Fibrinolytic system
ALL ACTIVATED BY CLOTTING FACTOR XII
Main Cell Involved in Inflammation
Neutrophils the main cell to mediate effects of inflammation (2-3x bigger than RBCs) but needs to get in to area.
If need more - access bone marrow.
Acute Inflammatory Response: 2. Increased Vascular Permeability
- Small blood vessels lined by endothelial cells. In some tissues, there are areas of endothelial cell thinning = FENESTRATIONS. Allow passage of small materials via diffusion OR ultrafiltration.
- -High colloid osmotic pressure inside vessel (due to plasma proteins) draws things INTO vessels.
- -In acute inflammation, capillary hydrostatic pressure increases AND plasma proteins escape into extravascular space resulting in increased colloid osmotic pressure.
- -MUCH more fluid leaves vessels. Net escape of protein-rich fluid is called exudation.
Lab Measurements of Acute Inflammation
- Raised neutrophil count in the peripheral blood (normally 40%)
- Increased erythrocyte sedimentation rate (ESR).
- Increase in blood concentration of certain proteins produced by the liver in response to acute inflammation (C-reactive protein)
Chronic Inflammation characterized by:
In contrast to acute inflammation (which is manifested by vascular changes, edema, and leukocyte infiltration)
A) Infiltration of mononuclear cells (agranulocytes): macrophages, lymphocytes, plasma cells
B) Tissue destruction
C) Fibrosis
2 Types of Inflammation
2 Types of Inflammation
- Acute: short-lasting (few days) associated with exudation (escape from blood vessels) of plasma and migration of neutrophils (most abundant WBCs).
EXAMPLES: soar throat, scratch, burn, insect bite - Chronic: longer-lasting, associated with presence of lymphocytes and macrophages and the blood vessels and connective tissue proliferation.
Chronic Inflammation: MPS
Mononuclear Phagocyte System (MPS) consists of monocyte cells that arise from a common precursor in the bone marrow.
-From the blood, monocytes migrate into tissues and transform into macrophages (liver, Kupffer cells; alveolar macrophages)
- Macrophages may be “activated”; a process that results in an increase in cell size and levels of lysosomal enzymes, and greater ability to phagocytose
- Following activation, the macrophages secrete a wide variety of active products (enzymes, plasma proteins, NO - nitric oxide)) that mediate tissue destruction and fibrosis.
Neutrophil Emigration
Neutrophils and macrophages can insert pseudopodia (part that pulls neutrophil) between endothelial cells, migrate through the gap created between the endothelial cells, and then on through the basal lamina into the vessel wall and enter extravascular space
(ONLY IN VEINS?)
Phagocytosis
process where cells (like neutrophils and macrophages) ingest solid particles. After adhesion the phagocyte then ingests the attached particle by sending pseudopodia around it forming phagocyte vacuole (also called phagosome) which is bounded by cell membrane.
Acute Inflammatory Response: 1. Changes in Vessel Caliber
- Vasoconstriction followed by vasodilation (active hyperemia) lasting 15 min to several hours.
- -Can increase bood flow up to 10-fold.
- -Blood flow slows due to plasma escaping causing increased blood viscosity.
- -Blood cells begin to flow near vessel wall
- -“Pavementing” - leukocytes adhere to vascular epithelium.
Effects of Acute Inflammation
- Functio Leasa (Loss of function)
Movement of an inflamed area is consciously and reflexivly inhibited by pain, while severe swelling may physically immobilize the tissues.
Chemical Mediators
Chemical Mediators (Histamine)
Best known,
EFFECTS: Vasodilation, Vascular Permeability
CELLS: mast cells, basophil and eosinophil leukocytes, and platelets.
Histamine release from those sites (for example, mast cell degranulation) is stimulated by complement components C3a and C5a, and by lysosomal proteins released from neutrophils.
Effects of Acute Inflammation
- Tumor (Swelling)
Swelling results from edema, the accumulation of fluid in the extra vascular space as part of the fluid exudate.
Types of Phagocytosis by Neutrophils
Intracellular killing - neutrophils contain 2 kinds of noxious agents:
- -Oxygen dependent- neutrophils produce hydrogen peroxide which produce noxious agents
- -Oxygen independent- neutrophis enzyme bacteroferrin binds iron required for bacterial growth
Margination of Neutrophils
In the normal circulation, cells are confined to the central (axial) stream in blood vessels, and do not flow in the peripheral (plasmatic) zone near to the endothelium. However, loss of intravascular fluid and increase in plasma viscosity with slowing of flow at the site of acute inflammation allow neutrophils to flow in this plasmatic zone. The adhesion of neutrophils to endothelium causes them to aggregate along the vessel walls in a process termed margination.
Effects of Acute Inflammation
- Rubor (Redness)
- Calor (Heat)
- Tumor (Swelling)
- Dolor (Pain)
- Functio Leasa (Loss of function)
What changes occur to cause inflammatory response?
- Vasoconstriction followed by VASODILATION
- Increased permeability of blood vessels. Allows for:
- Escape of cells from the blood into the tissues.
Systemic Effects of Acute Inflammation
- Constitutional symptoms
Including malaise, anorexia and nausea. Weight loss is common when there is extensive chronic inflammation.
Process of acute inflammation
- Occupation of exudate
- Killing of bacteria
- Removal of dead tissue