L6

Question 1

CHEMICAL MEDIATORS OF INFLAMMATION?

Answer 1

Def. : Chemical substances released from the cells, the plasma, or damaged tissue itself.

Co-ordinate the development of the inflammatory response.

Question 2

Chemical mediators, They are broadly classified into 2 groups:

Answer 2

i) mediators released by cells; and
ii) mediators originating from plasma.

Question 3

The inflammatory response
6

Answer 3

1-Vasoconstriction
2-Vasodilation
3-Increased vascular permeability
4-Emigration, chemotaxis
5-Phagocytosis
6-Tissue destruction

Question 4

Properties of chemical mediators

Answer 4

o Active mediators are produced in response to various stimuli
o Most of chemical mediators can stimulate the release of other mediators.
o Amplify and maintain the inflammatory response o Most of these are short lived

o Releasing stimuli:
• Direct physical , chemical or mechanical injury
• Microbes or their toxins
• ECM fragments
• Fragments of complement system e.g C3a and C5a
• Thrombin for most of cellular mediators
• Immune complexes
• Binding of IgE- Ag- complexes (for vasoactive amines)
• Cytokines (IL-1, IL-8 for vasoactive amines), (TNF, IFNγ for free radicals )
• TXA2, ADP for PAF

o Mechanism of action:
– Receptor-ligand interactions
– Direct enzymatic activity
– Mediate oxidative damage

Question 5

Chemical mediators released by cells ? 6

Answer 5

I-VASOACTIVE AMINES**: 1-Histamine 2- Serotonin 3- Neuropeptides

II-ARACHIDONIC ACID METABOLITES via 1- cyclo-oxygenase pathway (prostaglandins, thromboxane A2, prostacyclin) 2- lipo-oxygenase pathway (5-HETE,leukotrienes, lipoxins)

III-Platelet activating factor

IV-Cytokines (IL-1, TNF-α, TNF-β, IFN-γ, chemokines)

V-Lysosomal components** (from PMNs, macrophages)

VI-Free radicals (Oxygen metabolites, nitric oxide)

Question 6

ارجعي للجدول مهم جدًا