7/26/2019 WEEK 3 - infl--2.pptx

1/16

7/26/2019 WEEK 3 - infl--2.pptx

2/16

INFLAMMATION

7/26/2019 WEEK 3 - infl--2.pptx

3/16

(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.

7/26/2019 WEEK 3 - infl--2.pptx

4/16

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

7/26/2019 WEEK 3 - infl--2.pptx

5/16

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.

7/26/2019 WEEK 3 - infl--2.pptx

6/16

Chemical mediators of inflammation

7/26/2019 WEEK 3 - infl--2.pptx

7/16

7/26/2019 WEEK 3 - infl--2.pptx

8/16

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

7/26/2019 WEEK 3 - infl--2.pptx

9/16

II. LOCAL VASCULAR REACTIONS

7/26/2019 WEEK 3 - infl--2.pptx

10/16

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

7/26/2019 WEEK 3 - infl--2.pptx

11/16

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.

7/26/2019 WEEK 3 - infl--2.pptx

12/16

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

7/26/2019 WEEK 3 - infl--2.pptx

13/16

(

7/26/2019 WEEK 3 - infl--2.pptx

14/16

(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

7/26/2019 WEEK 3 - infl--2.pptx

15/16

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

7/26/2019 WEEK 3 - infl--2.pptx

16/16

(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