Inflammation Flashcards
What is Inflammation?
- Latin, Inflamatio, to set on fire
- Biological reaction to noxious stimuli such as microbes, burns and trauma
- Fundamentally protective process but may potentially be harmful leading to tissue injury
What are the two types of inflammation?
- Acute inflammation
- Chronic Inflammation
What are the 5 clinical signs of acute inflammation
- Rubor (redness)
- Tumour (Swelling)
- Calor (Heat)
- Dolor (Pain)
- Functio Laesa (Loss of function)
What is acute inflammation?
- Rapid host response to deliver leucocytes and plasma proteins such as antibodies to the sites of infection or tissue injury
Acute inflammation protects the body from further injury in response to what?
- Infections
- Trauma (blunt or penetrating)
- Burns/frostbite (thermal and chemical)
- Allergic reactions
- Tissue necrosis
How fast does acute inflammation occur and last?
- Occurs immediately and lasts hours-days
What reactions does acute inflammation consists of?
- Consists of vascular and cellular reactions
What are the three major components of acute inflammation? Explain them
- Vascular dilation- to increase blood flow
- Structure changes - in the microvasculature to allow plasma proteins and leukocytes to leave the circulation
- Emigration - of the leukocytes from the microvasculature, their accumulation in the injury site and their activation to eliminate the offending agent
What happens in Vascular reaction
- Vessel dilation and increased blood flow
- Leakage of plasma fluid and protein
- Leukocyte emigration and accumulation in the site of injury
What happens in vessel dilation and what is its purpose
- One of the earliest signs of acute inflammation - quick
- To increase blood flow
- Results in heat and redness (hyperaemia)
- Induced by the actions of several mediators on VSM: Histamine, Bradykinin, NO
What are the 3 mediators of vascular reactions?
- Histamine
- Bradykinin
- Nitric Oxide
What is the source and function of Histamine
- Source: Mast cells, basophils, platelets
- Function: Arteriole dilation, increased of venous permeability
What is the Source and Function of Bradykinin
- source: kinin system
- Function: Vasodilation, increase vascular permeability, pain
What is the source and function of Nitric oxide
- Source: Endothelial cells
- Function: Vasodilatation
What happens in Increased vascular permeability (leakage)
- A hallmark of acute inflammation
- Allow plasma fluid and protein to escape from the circulation into extracellular tissue
- The cause of oedema
Explain the mechanisms of Increased vascular permeability
- Endothelial cell contraction to increase intracellular spaces
- Endothelial cell injury and detachment
- Increased transport of fluid and protein through the endothelial cells
What is Leukocyte recruitment?
- Movement of leukocytes from vessel lumen to interstitial tissue is called extravasation
What happens in extravasation
- Leukocyte adhesion to endothelium
- Endothelial adhesion molecules: P-selectin, E-selectin, CD34, ICAM-1, VCAM-1 - Leukocyte migration through endothelium
- Chemotaxis of leukocytes
- A process that leukocytes emigrate toward the site of injury driven by substances called chemoattractants
What are the Cellular components of the Acute inflammation?
- Leukocytes - some act as phagocytes; others release enzymatic granules
- Migration of these leukocytes is a critical step of inflammation
- Initially phagocytic cells - neutrophils followed by monocytes
- Produce inflammatory mediators that maintain the inflammatory response
What is Chemotaxis?
- A process that leukocytes are attracted by chemotactic agents tot eh site of injury once outside of the blood vessel
Name Chemoattractants
- Exogenous: bacterial products
- Endogenous: complement components, cytokines, products of lipoxygenase pathway (leukotriene B4)
Explain Leucocyte recognition through leukocyte receptors
- Receptor for microbial products: Toll-like receptors (TLRs)
- G protein-coupled receptors: Recognise short bacterial peptides containing N-formyl methionyl residues
- Receptors for opsonins: Examples of opsonins - antibodies, complements, lectins
- Receptor for cytokines: INF
What is Phagocytosis?
- Removal of the offending agents
Explain Phagocytosis
- Recognition and attachment
- Engulfment
- Engulfed particle fuses with lysosome to form phagolysosome
- Degranulation - Killing
- ROS (oxidative burst generated by NADPH oxidase)
- Other lysosomal enzymes
Name Acute inflammatory cytokines
- TNF-alpha
- IL-1
- IL-6
- chemokines
What is the sources for TNF-alpha?
- Macrophages, mast cells, T lymphocytes
What is the sources for IL-1?
- Macrophages, endothelial cells, epithelial cells
What is the sources for IL-6?
- Macrophages, other cells
What is the sources for Chemokines?
- Macrophages, endothelial cells, T lymphocytes, mast cells, other cells
Name 4 Morphological patterns for acute inflammation
- Fibrinous
- Purulent
- Serous
- Ulcerative
What is Fibrinous? (Morphological patterns)
- Characterised by fibrinous exudate which can lead to scar formation and limitation of function
What is Purulent? (Morphological patterns)
- Pus filled fluid consisting of neutrophils and dead cells, typically caused by staphylococcal infections
What is Serous? (Morphological patterns)
- Copious effusion of non-viscous serous fluid. Typical example is skin blister
What is Ulcerative? (Morphological patterns)
- Necrotic loss of tissue from the surface, exposing lower layers leading to formation of an ulcer
What are the outcomes of acute inflammation?
- Complete resolution: injury is limited or short-lived, with little tissue damage
- Healing by connective tissue replacement (fibrosis): Substantial tissue damage, fibroblasts grow into the area of damage
- Progression to chronic inflammation
