Acute Inflammation Flashcards
Key Features of acute inflammation
edema
dilated vessels
infiltration by activated neutrophils (early) and macrophages (later
systemic effects of acute inflammation
fever neutrophilia fatigue Loss of appetite increased acute phase proteins in blood
outcomes of acute inflammation
resolution
healing by fibrosis
abscess formation
chronic inflammation
important mediators in vasodilation
histamine
prostaglandins
NO
important mediators in increasing vascular permeability
serotonin histamine C5a C3a leukotrienes
important mediators in leukocyte activation and chemotaxis
C5a
leukotriene B4
bacterial products/chemokines
What is inflammation?
universal response to tissue damage by harmful stimuli:
mechanical trauma
tissue necrosis
infection
What is the purpose of inflammation?
destroy (or contain) the damaging agent
initiate repair processes
return the damaged tissue to useful function
Define hyperemia
Relaxation of vascular smooth muscle leads to engorgement of tissue with blood in the first phase of acute inflammation
Which adhesion molecules are expressed by activated neutrophils to make contact with endothelial cells?
integrins and selectins
What is the regular lifespan of a mature neutrophil?
3 days
How do neutrophils kill bacteria and insulting agents before undergoing apoptosis?
Generate respiratory burst to produce hydrogen peroxide and other reactive oxygen species
How are dead neutrophils cleaned up?
by macrophages that arrive by 2nd/3rd day after injury
Which plasma proteins are involved in acute inflammation?
C5a
C3a
immunoglobulins
fibrinogen and fibrin
How long does acute inflammation last?
hours to days depending on the type and severity of the tissue damage
What is pavementing?
neutrophils lining up at the periphery of a vessel waiting to extravasate
What is the typical acute inflammatory exudate made of?
water
proteins (fibrin)
neutrophils
What are the mediators of increased vascular permeability?
vasoactive amines serotonin (5-hydroxytryptamine (5-HT)) histamine C5a and C3a leukotrienes C4, D4, and E4 platelet activating factor (PAF).
Describe Suppurative (purulent) inflammation
rich in neutrophil leukocytes
due to of infection by bacteria
What is pus?
mixture of neutrophils (viable and dead), necrotic tissue, and tissue fluid in the acute inflammatory exudate
What is an abscess?
a circumscribed collection of semi-liquid pus
What is the cause of destruction of tissue in acute inflammation?
release of neutrophil lysosomal enzymes
destruction by bacteria
What are pyogenic bacteria?
Bacteria which produce purulent inflammation
What are examples of pyogenic bacteria?
Staphylococci Streptococcus pyogenes Streptococcus pneumoniae E. Coli Neisseria meningitidis Neisseria gonnorrhoeae
What is contained in the exudate of fibrinous inflammation?
high plasma protein content (fibrinogen converted to fibrin)
Where is fibrinous inflammation usually found?
membrane-lined cavities such as the pleura, pericardium and peritoneum, where the fibrin strands form a mat-like sheet causing adhesion between adjacent surfaces
What is transudate?
fluid with a low plasma protein and cell content (transudate = specific gravity
What is an exudate?
specific gravity >1.020 and protein content >25 g/L
When is a transudate commonly seen?
in the skin in response to a burn
What are the three big cytokines involved in acute inflammation (and mediates fever)?
interleukins 1 & 6, tumour necrosis factor (TNF) and prostaglandins
What are the four end outcomes of acute inflammation?
resolution
healing by fibrosis/scar formation
abscess formation
chronic inflammation
Describe resolution
complete restitution of normal tissue architecture and function that can only occur if the CT framework of the tissue is intact and the tissue involved has the capacity to replace any specialised cells that have been lost
Describe healing by fibrosis
substantial damage to the CT framework and/or the tissue lacks the ability to regenerate specialised cells
defect becomes filled by ingrowth of a specialised vascular connective tissue called granulation tissue
What is the two types of granulation tissue and what are their differences?
vascular granulation tissue - proliferating leaky capillaries, fibroblasts and inflammatory cells
fibrous granulation tissue - vessels regress, collagen laid down and is remodelled into orderly pattern to withstand tensile stresses
occurs for many weeks
What is healing by primary intention?
wound edges are in close apposition and the actual defect is minimal, healing occurs quickly with a small amount of granulation tissue and is termed
What is healing by secondary intention?
large tissue defect filled with blood clot and a variable amount of tissue debris. In this case, organization and filling of the defect by granulation tissue will take longer
What is a feature of inactive fibrobalsts (after they have finished laying down collagen?)
small, condensed nuclei
What does healing of the skin or mucous membrane require
epithelialization of the surface by proliferation of epithelium at the edges of the defect
What bacteria will cause an abscess formation?
pyogenic bacteria
What is liquefaction?
Liquefactive necrosis of the cells inside an abscess that is basically pus
What is an abscess?
chronic inflammation surrounding acute inflammation (dead neutrophils and viable bacteria forming pus in the middle)
Are the bacteria inside the abscess alive?
Yes
What is a chronic abscess?
an abscess encapsulated by granulation and fibrous tissue
