Flashcards in Inflammation and Healing Deck (94)
what is the effect of histamine?
increases vascular permeability
describe the role of tissue macrophages in acute inflammation
secrete chemical mediators that attract neutrophil polymorphs to the site
describe the role of the lymphatics in acute inflammation
channels dilate, and drain away the oedema fluid, limiting swelling.
antigens are carried to regional lymph nodes for recognition by lymphocytes.
what is the major role of neutrophil polymorphs in acute inflammation?
describe the steps of phagocytosis
1. adhesion of particle to cell surface (opsonisation facilitates)
2. ingestion of particle by sending out pseudopodia
3. fusion of lysosomes with the phagosome - phagolysosome
4. intracellular killing of microorganism
list the five terms used to describe special macroscopic appearances of acute inflammation - as dependent on the type of tissue involved and the type of agent provoking the inflammation.
suppurative (purulent) inflammation
necrotising (gangrenous) inflammation
describe some beneficial effects of acute inflammation
dilution of toxins - allows them to be carried away in lymphatic.
entry of antibodies - phagocytosis, toxin neutralisation.
transport of drugs (antibiotics) to inflamed area
fibrin formation impedes movement of microorganisms.
describe some harmful effects of acute inflammation
swelling - e.g. airway obstruction
inappropriate inflammatory response - type 1 hypersensitivity reactions (e.g. hayfever)
what factors determine the outcome of acute inflammation?
type of tissue involved.
amount of tissue destruction.
both of these depend on nature of injuring agent.
what is the usual result of acute inflammation?
what causes acute inflammation to progress to suppuration?
what causes acute inflammation to progress to organisation?
what causes acute inflammation to progress to chronic inflammation?
persistent causal agent
what conditions favour resolution of acute inflammation?
minimal cell death/tissue damage.
occurred in organ with regenerative capacity (e.g. liver)
rapid destruction of causal agent
rapid removal of fluid/debris - good local vascular drainage.
what is pus?
a mixture of living/dying/dead neutrophils and bacteria, cellular debris and possibly globules of lipid
what conditions favour progression of acute inflammation to organisation?
large amounts of fibrin.
lots of necrotic tissue.
exudate and debris not removed/discharged
what are the systemic effects of inflammation?
reactive hyperplasia of reticuloendothelial system.
what are the predominant cells seen in chronic inflammation?
lymphocytes, plasma cells and macrophages
(also fibroblasts and multinucleate giant cells)
list the causes of chronic inflammation
primary chronic inflammation
progression from acute inflammation
recurrent episodes of acute inflammation
give some examples of causes of primary chronic inflammation
TB, leprosy, viral infections - resistance to phagocytosis.
endogenous - necrotic adipose tissue, bone
exogenous - silica, asbestos, sutures, prostheses
chronic IBD eg ulcerative colitis
primary granulomatous diseases - Crohn's, sarcoidosis
what are the macroscopic appearances of chronic inflammation?
chronic abscess cavity
thickening of wall of a hollow viscus
describe the cellular infiltrate seen in chronic inflammation
lymphocytes, plasma cells and macrophages.
possibly a few eosinophil polymorphs, but no neutrophil polymorphs.
some macrophages may form neutrophil giant cells.
describe the differences between macrophages and neutrophil polymorphs
macrophages can ingest a wider range of materials.
neutrophil polymorphs last 3 days - destroy themself when they ingest microorganisms.
Macrophages are long-lived - if they can't kill ingest microorganisms, they will harbour them.
give some examples of organisms that can survive inside macrophages
mycobacteria - M tuberculosis and M leprae.
what are macrophages derived from? what system does this make them part of?
mononclear phagocyte system aka reticuloendothelial system.
define a granuloma
aggregation of epithelioid histiocytes
what cell types does a granuloma contain?
also possible - lymphocytes and histiocytic giant cells
give some examples of granulomatous disease
describe the morphology of an epithelioid histiocyte
vague histological resemblance to epithelial cells.
large vesicular nuclei
arranged in clusters.