MCBoM- Chemical mediators of Inflammation Flashcards Preview

1st year Medicine > MCBoM- Chemical mediators of Inflammation > Flashcards

Flashcards in MCBoM- Chemical mediators of Inflammation Deck (15):
1

Vasoactive amines

HISTAMINE
Widely distributed, from mast cells, basophils and platelets
Released by these cells in response to physical injury or immune reaction
Causes dilation of arterioles and increased vascular permeability of venules
SEROTONIN
In platelets and enterochromaffin cells
Similar action to histamine

2

Plasma proteases- Complement system

Found in plasma
Requires activation: C1 by classical or lectin pathways, C3 by alternative pathways
Causes lysis of microbes by MAC (membrane attack complex) C5-9
C3b -opsonin
C5a -chemotactic agent
C3a and C5a -anaphylotoxins

3

Plasma proteases- Coagulation system

Found in plasma
Requires activation
Converts soluble fibrinogen to fibrin
Some play a role in inflammation:
thrombin-> increased leukocyte adhesion, fibroblast proliferation
fibrinopeptide-> increased vascular permeability, chemotaxis
factor Xa-> increased vascular permeability, leukocyte exudation

4

Plasma proteases- Kinin system

Found in plasma
Requires activation
Activation causes release of bradykinin, leading to increased vascular permeability, contraction of smooth muscle, vasodilation, pain

5

Arachidonic acid metabolites

AA is 20 carbon polyunsaturated fatty acid
Derived from diet or by conversion from lenoleic acid (essential FA)
Esterified in membrane phospholipids
Metabolites are eicosanoids, synthesised by cyclooxygenase and lipooxygenase

6

Cytokines

Proteins mainly produced by lymphocytes and macrophages, modulates function of other cell types
Monokines- produced by monocytes
Lymphokines- produced by lymphocytes
Chemokines- cytokines that have the ability to stimulate leukocyte movement (chemokinesis) and directed movement (chemotaxis)
IL1 and TNF are major mediators of inflammation
-> more sleep, decreased appetite, more acute phase proteins

7

Nitric Oxide

Soluble gas produced by endothelial cells, macrophages and specific neurones in brain
Short half life, so paracrine effect (local)
Functions:
-vasodilator
-antimicrobial activity
-pathogenesis of shock
-decreased leukocyte adhesion and migration
-decreased platelet aggregation and adhesion

8

Platelet Activating Factor (PAF)

From platelets, basophils/mast cells, neutrophils, monocytes/macrophages, endothelium
Functions:
-activation of platelets
-chemotaxis
-bronchoconstriction
Low concs-> vasodilation, increased vascular permeability
High concs-> vasoconstriction

9

Lysosomal constituents of leukocytes

Neutrophils and monocytes contain lysosomal granules
-Larger azurophilic/primary granules
-Smaller specific/secondary granules

10

Vasodilation

-Prostaglandins
-Nitric Oxide
So more blood to site of injury, provides WBCs and antibodies

11

Increased vascular permeability

-Vasoactive amines
-C3a and C5a
-Bradykinin
-Leukotrines
-PAF
So chemicals can leave the blood to get to the tissue, site of injury

12

Chemotaxis and leukocyte activation

-C5a and leukotrines
-Chemokines
-Bacterial products
To guide WBCs to site of injury so can activate and destroy injurious agent

13

Fever

-IL1, IL6, TNF
-Prostaglandins

14

Pain

-Prostaglandins
-Bradykinin

15

Tissue damage

-Neutrophil and macrophage lysosomal enzymes
-Oxygen metabolites (free radicals produced by cell)
-Nitric Oxide
To protect the body, just some collateral damage