acute and chronic inflammation week 6 Flashcards
what is acute inflammation
a series of protective changes occurring in living tissue as a response to injury
what are the cardinal signs of inflammation
- redness (rubor)
- heat (calor)
- swelling (tumor)
- pain (dolor)
- loss of function
causes of acute inflammation
- micro-organisms (infection)
- mechanical (trauma) injury to tissue
- chemical - upset stable environment (change in ph or urine or bile somewhere it shouldn’t be
- physical - extreme conditions (cold, heat, ionising radiation)
- dead tissue (cell necrosis irritates nearby cells)
- hypersensitivity
where does process of acute inflammation take place
microcirculation
steps of acute inflammation
- changes in vessel radius - flow
- change in the permeability of the vessel wall - exudation
- movement of neutrophils from the vessel to the extravascular space
in acute inflammation, what are the changes in vessel radius
- transient arteriolar constriction (short time, protective)
- local arteriolar dilatation (active hyperaemia)
- relaxation of vessel smooth muscle
in acute inflammation, what causes increased permeability
locally released chemical mediators (make lining of the vessels leak, fluid and protein leak into the adjacent tissue)
in acute inflammation, what is the effect of increased permeability
- net movement of plasma from capillaries to extravascular space. this process is exudation
- viscosity of plasma increases because all that is left is big molecules so rate of flow is slower
in acute inflammation, what is leaked in exudate
exudate is fluid rich in protein, includes immunoglobulin and fibrinogen
in acute inflammation, what is effect of exudation
oedema formed
what is the result of swelling
swelling causes pain which reduces function
what is different about flow in vessels in inflammation
normally white blood cells would be in centre of vessel and red blood cells would surround them but in inflammation white blood cells migrate to outside perimeter of vessel and red blood cells congregate in middle of vessel
what are the phases of emigration of neutrophils
- margination - neutrophils move to endothelial aspect of lumen
- pavementing - neutrophils adhere to endothelium
- emigration - neutrophils squeeze between endothelial cells (active process) to extravascular tissues
what is diapedesis
diapedesis is when you sometimes get a red blood cell following a neutrophil through the endothelial cells (passive because no muscle helping RBC)
what is the ideal outcome of acute inflammation
- inciting agent isolated and destroyed
- macrophages move in from blood and phagocytose debris then leave
- epithelial surfaces regenerate
- inflammatory exudate filters away
- vascular changes return to normal
what are the benefits of acute inflammation
- rapid response to non-specific insult
- cardinal signs and loss of function (transient protection of inflamed area)
- neutrophils destroy organisms and denature antigen for macrophages
- plasma proteins localise process
- resolution and return to normal
what are the outcomes of acute inflammation
either:
- resoltion
- suppuration (pus formation)
- organisation (about tissue repair)
- chronic inflammation
in acute inflammation, what do neutrophils do
- mobile phagocytes (recognise foreign antigen, move towards it - chemotaxis, adhere to organism)
- granules possess antioxidants and enzymes (e.g. proteases)
- release granule contents
- phagocytose and destroy foreign antigen
what are the consequences of neutrophil action in acute inflammation
- neutrophils die when granule contents released
- pus produced (fluid, organisms, endogenous proteins)
- might extend into other tissues, progressing the inflammation
roles of plasma proteins in inflammation
fibrinogen - coagulation factor (clots exudate and therefore localises inflammation)
immunoglobulins in plasma specific for antigen
what are the mediators of acute inflammation
- molecules on endothelial cell surface membrane
- molecules released from cells
- molecules in the plasma
- molecules inside cells
what are the collective effects of mediators in acute inflammation
- vasodilation
- increased permeability
- neutrophil adhesion
- chemotaxis
- itch and pain
what are some cell surface mediators in acute inflammation
- ICAM - 1 helps neutrophils stick to endothelial cells
- p-selectin interacts with neutrophil surface
in acute inflammation, what are some mediators that are released from cells
- histamine causes vasodilation and increased permeability (results from IgE mediated reaction - allergic reaction)
- 5-hydroxytryptamine (serotonin) vasoconstriction, released when platelets degranulate in coagulation
- prostaglandins
- cytokines and chemokine
- nitric oxide
- oxygen free radicals