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
What are the 4 enzymatic cascade systems found in plasma?
- complement system
- the kinins
- the coagulation factors
- fibrinolytic system
What is the complement system?
cascade system of enzymatic proteins - activated during inflammatory system - helps get rid of pathogens and antigens
What are the coagulation factors function?
the conversion of soluble fibrinogen into fibrin - seals leaks
What is the fibrinolytic system?
lysis of fibrin into fibrin degradation products
How do neutrophils carry out their function?
- movement (chemotaxis)
- recognition of and adhesion to micro-organisms
- phagocytosis
- intracellular killing of micro-organisms
What are opsonins?
proteins that bind to extracellular materials and make them more adherent to phagocytic cells and more amenable to engulfment or ingestion
Why are opsonins important?
most micro-organisms are not recognised until they are coated in opsonins
these opsonins greatly enhance phagocytosis
How do opsonins work?
they bind to specific receptors on leucocytes (WBCs) and greatly enhance phagocytosis
What are the major opsonins?
Fc fragment of IgG
C3b - fragment of C3 generated by complement activation
Collectins - plasma proteins that bind to microbial cell walls
What is phagocytosis?
process in which cells such as neutrophils and macrophages ingest solid particles
What does acute inflammation look like?
- serous
- catarrhal
- fibrinous
- hemorrhagic
- suppurative
- membranous
- pseudomembranous
Serous?
protein rich fluid exudate
Catarrhal?
mucus hypersecretion
Fibrinous?
exudate contains plentiful fibrin
Hemorrhagic?
severe vascular injury
Suppurative?
production of pus
Membranous?
epithelium coated by fibrin
Pseudomembranous?
superficial mucosal slough
What is suppuration?
formation of pus - due to mainly neutrophils also bacteria, cellular debris
- caused almost always by an infective agent
What is an abscess?
a collection of puss surrounded by a membrane of sprouting capillaries, neutrophils and occasional fibroblasts
What happens to a drained abscess?
the abscess cavity collapses and is obliterated by organisation and fibrosis
How may deep seated accesses drain?
along a sinus tract or fistula
What is a fistula?
abnormal connection between two hollow spaces (blood vessels, intestine, hollow organs)
What is an ulcer?
a local defect or excavation of the surface of an organ or tissue that is produced by the sloughing of inflammatory necrotic tissue
What is sloughing/slough?
dead tissue sperating from living tissue
What is necrotic tissue?
death of cells or tissues due to injury/disease especially in a localised area of the body
Where is ulceration most commonly found?
- inflammatory necrosis of the mucosa - mouth, stomach, intestine
- chronic leg ulcers in those with circulatory disturbance
What are the beneficial effects of acute inflammation?
- dilution of toxins - (then can be carried away by lymphatics)
- entry of antibodies - (due to increased vascular permeability)
- fibrin formation - (impedes movement of microorganisms)
- transport of drugs - (eg antibiotics)
- delivery of nutrients and oxygen - (aided by increased fluid flow)
- stimulation of immune response - (fluid exudate containing antigens reaches local lymph nodes)
What are the harmful effects of acute inflammation?
- digestion of normal tissues
- swelling - eg. brain swelling, laryngeal oedema
- inappropriate inflammatory response - eg. type I hypersensitivity (allergic reaction)
What are the systemic effects of acute inflammation?
- pyrexia (fever) -
- constitutional symptoms
- reactive hyperplasia of the reticuloendothelial system
- haematological changes
Explain pyrexia in acute inflammation?
elevation in temperature may improve efficiency y of leukocyte killing and probably impairs the replication of many offending microorganisms
What are constitutional symptoms?
Constitutional symptomsrefers to a group ofsymptomsthat can affect many different systems of the body. eg. weight loss, malaise, nausea …
Explain weight loss in inflammation?
- due to negative nitrogen balance - especially when there is extensive chronic inflammation
What is reactive hyperplasia of the reticuloendothelial system?
?
What haematological changes can occur as a result of inflammation?
- increased erythrocyte sedimentation rate (rate at which red blood cells separate from serum)
- anaemia (low red blood cells)
- leukocytosis (increased white blood cells)
