Accute Inflammation Flashcards
(56 cards)
What is acute inflammation the driving force of?
The innate Immune response
- The response of living tissue to infection/damage
- Acute inflammation is the initial and essential process for innate immunity
How quickly does acute inflammation develop and how long does it last?
Develops quickly (mins-hours) and lasts a few hors to days
What are the 3 main interlinked processes of acute inflammation?
- Vascular dilation (change in blood vessel calibre)
- Increased vascular permeability - allows for cells and molecules to support inflammatory response
- Neutrophil activation and migration
What are the 4 main causes of acute inflammation?
Microbial infection
- Inflammation can be induced by microorganisms
Physical agents
- Physical trauma
- UV or other ionising radiation
- Heat (burns) or cold (frostbite)
Irritant and corrosive chemicals
- Acids and alkalis
- oxidising agents
- Infective agents may release specific chemical irritants which lead directly to inflammation
Tissue necrosis
- Lack of oxygen or nutrients due to inadequate blood flow (infarction)
What are the cardinal signs of acute inflammation according to Celsus?
Rubor (redness) - due to dilation of small blood vessel in damaged areas
Calor (heat) - due to increased blood flow (hyperaemia)
Tumor (swelling) - due to accumulation of fluid in extra vascular space (oedema)
Dolor (pain) - Stretching/distortion of tissue due to oedema. Chemical mediators bradykinin, prostaglandins induce pain
Loss of function - related to chronic inflammation
What are the vascular responses of acute inflammation?
- Small blood vessels adjacent to site of damage become dilated with increased blood flow
- Endothelial cells swell and partially retract - opening up of gaps between them
- Exudation - the vessels become ‘leaky’ and allow passage of water, salts and some proteins (blood flow slows)
- Endothelial cells activated to promote immune cells passage to damage tissues (mainly neutrophils and monocytes/macrophages)
- The endothelial cells can change what they express on their surfaces to change what they are attracting - so they can attract immune cells
What is the process involved in bacterial induced acute inflammation (gingivitis)?
- Bacteria trigger macrophages to release cytokines and chemokines
- Vasodilation and increased vascular permeability causes redness, heat and swelling and allows the passage of fluid and cells
- Inflammatory cells migrate into tissues, releasing inflammatory mediators that cause pain (cells and fluid aim to resolve inflammation)
What happens to capillaries in response to acute inflammation?
- Dilation of capillaries which increases the blood flow
- This is done by the opening of sphincters so a lot more blood is flowing to the area
What does oedema mean?
Excess of fluid
What does the inflammatory exudate provide to the affected tissue?
Fluids and salts
- Dilute toxins in tissues
- Allows diffusion of mediators across membranes
Glucose and oxygen
- Supports macrophages
Complement proteins and antibodies
- Opsonins for invading microorganisms - support phagocytosis
Fibrin (long insoluble filamentous protein)
- Polymerised via coagulation cascade
- Provides scaffold entrapping microbes and assist immune cell migration to area
- Important in blood clots
What are the chemical mediators of acute inflammation?
- Histamine
- Bradykinin
- Leukotrienes
- Serotonin
- Prostaglandins
What are the protein mediators of acute inflammation?
- Cytokines
- Chemokines
How is histamine formed?
Product of the breakdown of AA histidine
Where is histamine stored?
In granules of immune cells such as mast cells
How is degranulation of histidine to release histamine stimulated?
- Stimulated by C3a, C5a - complement
- Also caused by antigens
What are the roles of histamine?
- Role as neurotransmitter - itching (acts upon nerve fibres)
- Causes vascular dilation
- Multiple functions in immune response
What are prostaglandins the product of?
Fatty acid metabolism
What is the most abundant prostaglandin?
Prostaglandin E2 (PGE2)
What are the roles of prostaglandins in acute inflammation?
- Causes vascular dilation
- Regulate cytokine production from cells
- Regulate chemokine production - attracts immune cells
- Act on nerve fibres (neurotransmitter) - pain
- Involved in tissue remodelling
What are prostaglandins regulated by?
The enzyme Cyclo-oxygenase II (COX II)
What targets COX II enzyme?
NSAIDS (non steroidal anti inflammatory drugs)
What are plasma factor systems?
- Proteolytic cascades
- Stepwise activation involving formation of enzyme complexes and protein cleavage
What are the 4 plasma factors enzymatic cascades?
- Complement
- The kinin system
- Coagulation
- Fibrinolytic system
Are all 4 of the plasma factor enzymatic cascade systems interlinked?
Yes, the Hageman factor is important as it is the driver for most of these cascades
