3. Complement System Flashcards
What and how many proteins does the complement system consist of?
9 plasma proteins.
What does complement do to foreign organisms?
Opsonisation and phagocytosis.
What are the pathways that activate complement?
Classical, alternative, lectin.
How is complement activated in the classical pathway?
Antibodies bind to the surface of the microbe. Fc regions bind C1. C2, C4, C3 activates. C3 convertase activates and covalently binds to the microbe.
How is complement activated in the alternative pathway?
C3 gets close to the microbe surface and activates a convertase different to the lectin and classical pathways.
How is complement activated in the lectin pathway?
Lectin binds to unique carbohydrates specific to the microbe which then activates a similar convertase to that of the classical pathway.
What are lectins?
Carbohydrate-binding proteins.
What activates C5?
Convertases that are covalently bound to the surface of the microbe.
What is the membrane attack complex (MAP)?
A pore made up of C5, 6, 7, 8, and 9, which inserts into the membrane of the bacteria to cause lysis.
What are anaphylatoxins?
Small polypeptides generated by the cleavage of larger proteins.
What do anaphylatoxins do?
They are powerful chemoattractants that recruit and activate phagoctes.
What are the types of anaphylatoxins?
C3a, C4a, C5a.
