Flashcards in Acute / Chronic inflammation Deck (21):
Inflammation is the reaction of vascularised living tissue to local injury.
Mediated by the reaction of blood vessels to pro-inflammatory cytokines and chemokines, inflammation leads to the accumulation of fluid and immune cells at the site of infection.
Repair is the replacement of injured tissue either by
1. Regeneration of parenchymal cells
2.Fibroblastic or Glial "scar" tissue
Give 4 examples of where mechanisms of inflammation and repair can be harmful to the host.
Renal disease (accumulation of immune complexes)
Fibrous adhesions (fibrous bands may cause twisting of the bowel and may cause complete occlusion)
Exudate is the term used to describe the inflammatory extravascular fluid that contains a high protein concentration and a S.G > 1020
An ultra filtrate with a low protein concentration - mostly albumin and a S.G
A thick exudate rich in neutrophils and parenchymal cell debris.
What are the 4 cardinal signs of inflammation?
Rubor - REDNESS
Tumour - SWELLING
Calor - HEAT
Dolor - PAIN
What is meant by the "Triple Response" as termed by Sir Thomas Lewis in 1927?
Dull red line - Vasodilatation and increased blood flow
Wheal (Swelling of the stroke mark)
What changes occur in the vascular flow and calibre following a hard stroke mark on the skin?
Transient vasoconstriction of arterioles causes a white line to appear briefly on the skin.
This is followed by prolonged vasodilatation and increased blood flow, creating a red line on the skin.
Slowing of the circulation due to increased permeability of the local microvasculature - "Stasis".
Leucocyte margination and emigration.
In chemotaxis, what are the receptor/surface molecule interactions between the endothelial cells and immune cells being recruited from the circulation?
Neutrophil LFA-1 to Endothelial cell ICAM-1
Lymphocyte VLA-4 to Endothelial cell VCAM
Leukocyte PSGL-1 to Endothelial cell E-selectin
Since leukocytes continuously express cell adhesion molecules, what prevents unwanted chemotaxis?
Chemokine gradient draws leukocytes to the site of infection in order to satisfy their specific receptors for chemotactic agents.
Endothelial cells only upregulate the expression of cell adhesion molecules when there is inflammation. At rest, cell adhesion molecules such as P-Selectin are held in intracellular vacuoles called Weibel-palade bodies.
Histamine, thrombin and other pro-inflammatory triggers cause translocation of these W-P bodies to the cell's surface to allow the cell adhesion molecules to be expressed.
What are the 3 main chemotactic agents for neutrophils?
Leukocytes have specific receptors for the following chemotactic agents:
Complement components such as C5a and C3a
Products of the lipoxygenase pathway of arachidonic acid metabolism - leukotriene B4
What dominates in acute serous inflammation?
Mostly fluid, few cells
What dominates in acute suppurative inflammation?
Mostly dead cells, little fluid
What is inflammation of the lungs called?
What happens in acute membranous inflammation?
Give an example
Formation of an inflamed membrane over the tissue.
Pseudomembranous colitis caused by excessive antibiotic use, eliminating commensals in the gut, allowing Clostridium difficile to invade the tissue.
The presence of what cells is usually an indicator of chronic inflammation?
Lymphocytes and Macrophages
What is another sign of chronic inflammation?
Proliferation of fibroblasts and increased connective tissue - Fibrosis
Also the proliferation small blood vessels.
True or False: Chronic inflammation can develop as a result of repeated bouts of acute inflammation
This may be caused by prolonged exposure to non-degradable substances, autoimmune diseases or persistent infections by intracellular organisms.
What is a granuloma?
Granulomas are spherical collections of lymphocytes and macrophages that form at the area of injury.
If the cause of the inflammation is an infectious agent, then these granulomas are called Caseous Epithelioid Granulomas and the core of these granulomas undergoes necrosis.
If the cause of the inflammation is non-infectious (silica, paraffin oil, asbestos fibres or other foreign or inorganic material), then the granulomas are called Noncaseating Epithelioid Granulomas.
Both types of granulomas undergo healing by fibrosis.