Immunity And Coagulation 2 Flashcards
Complement system
part of the immune system that enhances (complements) the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism,.
It promotes inflammation, and attacks the pathogen’s cell membrane.
if stimulated by
When stimulated by one of several triggers, protease enzymes cleave specific proteins to release cytokines which initiates a cascade of further cleavages.
complement activation
The end result of this complement activation or complement fixation cascade is stimulation of phagocytes to clear foreign and damaged material, inflammation to attract additional phagocytes, and activation of the cell-killing membrane attack complex.
complement system is composted of
Anaphylatoxins
Chemotactic factors
Opsonins (C3b) =
Anaphylatoxins
cause histamine release resulting in vasodilation and increased capillary permeability to improved access to plasma proteins
Chemotactic factors
attract phagocytes to the area
Opsonins (C3b) =
Cause coating of bacteria promoting phagocytosis
Kinin system
The kinin system interacts very closely with the clotting system.
Both can be activated by activation of Hagemans factor (XII)
final product of the kinin system
bradykinin dilates blood vessels.
Bradykinin also acts with
prostaglandin to initiate pain, smooth muscle contraction and increase vascular permeability
Role of cytokines
Cytokines are protein or lipid molecules secreted by cells as a means of communicating and affecting either pro-inflammatory or anti-inflammatory responses.
Some examples include of cytones
Interleukins (IL) –secreted by helper T cells
Interferons (IFN) - –secreted by helper T cells
Tumour necrosis factor (TNF)
C-reactive protein (CRP
Transforming growth factor (TGF)
Inflammation control
Each of the plasma protein systems when activated will initiate activation of the other systems.
Inflammation is critical for human survival and therefore activation must be guaranteed regardless of the cause of injury
Biochemicals released during inflammation are extremely potent and therefore require moderating and control to keep them localised to injured tissue.
Moderation of inflammation occurs
through the production of counter biochemicals which neutralise the effect of the inflammatory biochemical.
Examples of moderation
Plasma entering the tissues (oedema) contains enzymes that destroy inflammatory chemicals
Histaminase de-activates histamine
Thrombin activates plasminogen to form plasmin and plasmin breaks down clots
The clotting system activated
Clotting can be activated by substances released during injury eg collagen, proteinases, and plasmin as well as from endotoxins released by infective agents.
Blood clotting can be activated by one of two pathways
Extrinsic/tissue activation
Intrinsic/contact activation-
Extrinsic/tissue activation
mostly due to injury
Intrinsic/contact activation-
abnormal vessel walls
Initial damage to blood vessels causes
myogenic spam which constrict the vessel and reduces flow.
Spasm may last a few minutes to hours to allow for coagulation.
Activation of the clotting cascade also activates
fibrinopeptides A and B which enhance the inflammatory response.
Fibrinopeptides (esp B) are chemotactic for neutrophils and therefore increase vascular permeability and enhance the effect of bradykinin (kinin system)
