WEEK 3 - infl--2.pptx
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Transcript of WEEK 3 - infl--2.pptx
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INFLAMMATION
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(A) Acute Inflammation
It is characterized by the presence of fluid exudate,fibrin threads and leucocytesand caused by an irritant
of short duration.
The acute inflammatory reaction consists of:
I. Local tissue damage.
II. Local vascular reactions.
III. Local reaction of histocytes.
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The hotness found in the inflamed area is resulted
from:
Vasoconstriction of arterioles
Vasoconstriction of venules Vasodilatation of arterioles
Vasodilatation of venules
Vasostenosis
Pyrogenic substances are released from the bacteria,
virus and dead leucocytes responsible for;
Fever
Loss of function
Oedema
Pain
Redness
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I-LOCAL TISSUE DAMAGE
Occurs at the centre of the inflamed area as the
causative agent is at its maximum action. Thecentral cells are killed, i.e. necrosis.
This local damage of cells together with the
inflammatory agent trigger the release andactivation of chemical substances called chemicalmediators.
These chemical mediators play an important role inpromoting the vascular and cellular changes in theinflamed area.
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Chemical mediators of inflammation
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II. Local vascular reactions.
A- Transient Vasoconstriction
(1) Transient Constriction of the Blood Vessels
(2) Transient rapid blood flow
B- Persistence Vasodilatation
(3) Dilatation of the Blood Vessels
(4) Slowing of the Blood Stream (Stasis)
C- Inflammatory Exudate
(5)- Fluid Exudate(6)- Cellular Exudate
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II. LOCAL VASCULAR REACTIONS
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A- Transient Vasoconstriction
(1) Transient Constriction ofthe Blood Vessels: Causedby a direct stimulating actionof the irritanton the vascularwall.
Vasoconstriction is aprotective mechanism andlasts for seconds to minutesonly.
(2) Transient rapid bloodflow: resulted fromvasoconstriction of bloodvessels
B P i t V dil t ti
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B- Persistence Vasodilatation(3) Dilatation of the Blood Vessels:
a-Direct action of histamineon thevascular wall.
b-The dilatation of the arteriolesandcapillarieswith increase in the bloodflow is called active hyperaemia.
c-The inflamed area becomes red andhot.
(4) Slowing of the Blood Stream (Stasis):Caused by:
(a) Increased viscosityof the blood(the red blood cells become moreconcentrated)due to increase ofpermeability of the blood vessels andformation of the inflammatory fluidexudate(protein-rich fluid moves intothe extravascular tissues).
(b)Most of the capillaries in the inflamedarea open anddilate.
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Formation of transudates and exudates. A, Normal process (no fluid loss or gain)
B, A transudate is formed when fluid leaks out because of increased hydrostatic
pressure or decreased osmotic pressure. C, An exudate is formed in inflammation
because vascular permeability increases as a result of increased interendothelial
spaces
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(
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(c e n amma ory xu a e5- Fluid Exudate
Formation:The inflammatory fluid exudate
leaves the dilated capillaries and venules due to:(1) Increased vascular permeability to plasma and its
proteins caused by histamine and kinins is the main
cause.
(2) Increased capillary hydrostatic pressure due todilatation of the arterioles and increased blood flow.
(3) Increased osmotic pressure of the interstitial tissue
fluid (decrease of intravascular colloid osmotic pressure)
. This acts as a suction force from the capillaries.
Intravascular
hydrostatic
pressure+
Intravascular
Colloid osmotic
pressure
=Edema
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Functions of Fluid Exudate (1) It dilutes toxins, chemicals and poisons, so
minimizes their effects.
(2) Brings antibodies from the blood to the siteof inflammation.
(3) Supplies nutrition for the cells and carriesaway waste products.
(4)Supplies fibrinogen which changes to fibrin.
Fibrin has the following functions:
(a) Forms a network upon macrophages move
towards the irritant. (b). Forms a network upon which fibroblasts
proliferate and start healing.
(c) Localizes infection by surrounding theinflamed area
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(3) Neurofibromatosis
A hereditary familialdisease transmitted as adominant trait. The disease
is characterized by:
(a) Multiple neurofibromaswhich appear as small firmnodules in the skin alongthe course of the
cutaneous nerves.
(b) Cafe au lait skinpigmentation.
(c) Pigmented irishamartomas called Lisch
nodules.
Malignant tumours:Malignant Schwannoma
(neurofibrosarcoma).
Multiple neurofibromas
Cafe au lait skin
Malignant NeurofibromaPlexiform Neurofibroma