Acute Inflamation Flashcards
What are the principle causes of acute inflammation? (4)
- microbial infections
- hypersensitivity reactions
- physical agents
- chemical agents
What are the physical characteristics of acute inflammation?
- red - rubor
- hot - calor
- swollen - tumour
- painful/tender - doll
- loss of function
What causes rubor?
dilation of blood vessels
What causes calor?
peripheral increase in temp
What causes tumour?
due to oedema - watery fluid accumulation
What cause dolor?
stimulation of nerve endings by pressure and chemical mediators
What happens in the vascular phase?
dilation and increased permeability
- endothelial cells well initially, then contract to increase space between them
- process is regulated by chemical mediators
- epithelial cells are not damaged
What happens in the exudative phase?
fluid and cells escape from permeable venues (small veins)
- net loss of fluid from vascular into interstitial space - resulting in tumour/oedema
What is exudate?
mass of cells and fluid that has seeped out of blood vessels or organs in inflammation
- high protein content
- proteins include immunoglobulins (antibodies)
- continuously removed by lymphatics
What are the differences between exudate and transudate?
transudate:
- no net flow out
- normal vascular permeability
- low protein content
What is the function of the lymphatic system in acute inflammation?
lymphatics are dilated - drain fluid from exudate - antigens are carried to lymph nodes - recognised by lymphocytes
What is lymphangitis?
inflammation of the lymph vessels
What is lymphadenitis?
inflammation of the lymph nodes
What is the diagnostic feature of acute inflammation?
neutrophil accumulation in the extracellular space
What are neutrophils?
the most common white blood cell
- very short lived
What are the functions of neutrophils?
- kill organisms
- degrade necrotic tissue
- ingest offending agents
- produce chemical mediators
- produce toxic oxygen radicals
- produce tissue damaging enzymes
What is chemotaxis?
the movement of a motile cell or organism in a direction corresponding to a gradient of increasing/decreasing concentration of a particular substance
What happens in neutrophil chemotaxis?
the neutrophils migrate towards sites of infection/inflammation
- cell surface receptors allow neutrophils to detect chemical gradients of molecules (chemotactic compounds) - these direct the path of their migration
- at the site of the antigen the concentration of chemotactic compounds tends to be higher
What do chemotactic compounds include?
- bacterial products
- some complement components
- products of neutrophil activity
What are chemical mediators of acute inflammation?
any messenger that acts on blood vessels, inflammatory cells or any other cells to contribute to an inflammatory response
- spread of an acute inflammatory response following an injury suggests chemical substances (chemical mediators) released from injured tissue spread outwards into uninjured areas
Where are chemical mediators derived from?
exogenous (from in cells) - endotoxins
endogenous (extracellular) - plasma, leukocytes, endothelial cells, fibroblasts
What do endogenous chemical mediators cause?
- vasodilation
- emigration of neutrophils
- chemotaxis
- increased vascular permeability
- itching and pain
What are plasma factors?
clotting factors - proteins that work together with platelets to clot blood