acute inflammation Flashcards

1
Q

what is the definition of acute inflammation?

A

fundamental response maintaining integrity of organism ( dynamic homeostatic mechanism)
series of protective changes occurring in living tissue as a response to injury

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2
Q

what are the cardinal signs of inflammation?

A
rubor  - redness
calor - heat
tumor - swelling
dolor - pain
loss of function
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3
Q

what is the aetiology of acute inflammation?

A

pathogenic organisms
mechanical trauma or injury to tissue (occurs in all injuries even those that are sterile)
Chemical - upset stable environment (acid or akali)
physical - extreme conditions such as heat, cold or ionising radiation
dead tissue - cell necrosis
HYPERSENSITIVITY

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4
Q

what is the process of acute inflammation?

A

series of events
localised to affected tissue
takes place in the microcirculation
result in the cardinal signs of inflammation

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5
Q

what is the microcirculation?

A

capillary beds, fed by arterioles and drained by venules
STARLING FORCES CONTROL FLOW ACROSS MEMBRANE
there is a dynamic balance, which is maintained by HYDROSTATIC AND COLLOID OSMOTIC PRESSURE and COMPARTMENTS AND PHYSICAL CONSTANTS
lymphatic channels and drainage
extracellular “space” and the fluid and molecules within it

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6
Q

what are the steps - pathogenesis - in acute inflammation?

A

changes in vessel radius - flow
change in the permeability of the vessel wall - exudation
movement of neutrophils from the vessel to the extravascular space

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7
Q

what changes take place locally in vessel radius and blood flow during acute inflammation?

A

transient arteriolar constriction
local arteriolar dilation - hyperaemia
relaxation of vessel smooth muscle
known as the triple response - flush,flare,wheal

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8
Q

what is the effect of increased arteriolar radius?

A

increased local tissue blood flow which results in observed redness and heat - active hyperaemia
poiseuille’s law

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9
Q

what is increased permeability and what happens when it increases.

A

localised vascular response
microvascular bed
endothelial leak - fluid and protein not held in the vessel lumen
locally produced chemical mediators

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10
Q

what are the effects of increased permeability?

A

net movement of plasma from capillaries to extravascular space
process is called exudate
exudate is the name given to the fluid which leaks
exudate is rich in protein
fluid loss - which leads to increased viscosity and decreased flow (stasis)

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11
Q

what are the effects of exudation?

A

oedema formed
oedema is an accumulation of fluid in the extravascular space
causes swelling in acute inflammation
swelling causes pain - reduce function

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12
Q

what is the pattern of normal laminar flow?

A

neutrophils on the inside, eryhtrocytes on the outside, plasma contained within the cell

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13
Q

what happens to laminar flow in acute inflammation?

A

red cells aggregate in the centre of the lumen
neutrophils found near the endothelium
neutrophil polymorphonuclear leukocyte (NPL) is most important cell

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14
Q

what are the phases of neutrophil emigration?

A

margination - neutrophils move to endothelial aspect of lumen
pavementing - neutrophils adhere to endothelium
emigration - neutrophils squeeze between endothelial cells to extravascular tissues

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15
Q

how would acute inflammation be resolved?

A
inciting agent is isolated and destroyed
macrophages move in from blood and phagocytose the debris; then leave
epithelial surfaces regenerate
inflammatory exudate filters away
vascular changes return to normal
inflammation resolves
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16
Q

what are the benefits of acute inflammation?

A

rapid response to non specific insult
cardinal signs and loss of function provide transient protection of inflamed area
neutrophils destroy organisms and denature antigen for macrophages
plasma proteins keep the process localised
resolution and eventual return to normal function

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17
Q

what are the possible outcomes of acute inflammation?

A

resolution
suppuration
organisation
chronic inflammation

18
Q

what do neutrophils do?

A
recognise foreign antigen
move to towards it - chemotaxis
adhere to organism
they release granule content which contain oxidants and enzyme
phagocytose and destroy foreign antigen
19
Q

what are some consequences of neutrophil action?

A

die after granule contents released
produce a mixture of fluid, bits of cells, organisms, endogenous proteins - pus
pus may extend into other tissues, progressing the inflammation

20
Q

what are the two plasma proteins involved in inflammation?

A

fibrinogen and immunoglobulins

21
Q

what are the roles of plasma proteins in inflammation?

A

fibrinogen is a coagulation factor which forms fibrin and clots the exudate - localises inflammatory process
immunogloblulins are part of the humoural immune response

22
Q

what are the mediators of acute inflammation?

A

molecules on endothelial cell surface membrane
molecules released from cells
molecules in the plasma

23
Q

what are some collective effects of mediators?

A
vasodilatation
increased permeability
neutrophil adhesion
chemotaxis
itch and pain
24
Q

why are cell surface mediators sticky?

A

adhesion molecules appear on endothelial cells e.g. to help neutrophils stick
P-selectin interacts with neutrophil surface

25
what molecules are released from cells during acute inflammation?
histamine - released is a result of local injury (IgE mediated). also causes vasodilatation and increased permeabilty serotonin - released when platelets degranulate in coagulation, causes vasoconstriction prostaglandins- promotes histamine effects and inhibits inflammatory cells leukotrienes - neutrophils, vasoactive omega-3-polyunsaturated fatty acids platelet activating factor cytokine and chemokines nitroc oxide oxygen free radicals
26
what four enzyme cascades interact in acute inflammation?
blood coagulation pathways fibrinolysis kinin system complement cascade
27
what are the immediate systemic effects of inflammation?
pyrexia feel unwell neutrophilia - raised white cell count
28
what are some longer term systemic effects of inflammation?
lymphadenopathy weight loss anaemia
29
what is suppuration?
formation of pus which is then surrounded by a pyogenic membrane
30
what is an abscess?
collection of pus under pressure single locule or multiloculated points and discharges collapses - healing and repair
31
what surrounds the abscess cavity?
an ingrowth of granulation tissue
32
what is a multiloculated abscess?
when pus bursts through the pyogenic membrane surrounding the original cavity to form more cavities
33
what is empyema?
when pus is in a hollow viscus, such as the pleural cavity
34
what is pyaemia?
pus discharge to the bloodstream
35
what is organisition?
an outcome of acute inflammation that is characteristic of granulation tissue, promotes healing and repair and leads to fibrosis and the formation of a scar
36
what is granulation tissue?
formation of new capillaries - angiogenesis | composed of fibroblasts, collagen and macrophages
37
what are some consequences of dissemination of acute inflammation?
spread to bloodstream -"septic" bacteraemia - bacteria in blood septicaemia - growth of bacteria in blood toxaemia - toxic products in blood
38
what are the effects of systemic infection?
shock - inability to perfuse tissues
39
what are the clinical signs of early septic shock?
``` tachycardia hypotension peripheral vasodilation pyrexia often sometimes haemorrhagic skin rash ```
40
what is the pathogenesis of septic shock?
systemic release of chemical mediators from cells into plasma decreased Systemic vascular resistance causes tachycardia because the heart rate is increased in order to maintain cardiac output bacterial endotoxin is released activation of coagulation - rash
41
what are the outcomes of septic shock?
rapidly fatal tissue hypoxia = cell death haemorrhage
42
summarise the outcomes of acute imflammation
``` resolution suppuration organisation dissemination chronic inflammation ```