Complement Anaphylatoxins (C5a, C3a, C4a)

The video tutorial explains the three pathways of complement activation, focusing on the role of C3 convertase in the lectin and classical pathways. It highlights the importance of anaphylatoxins, particularly C3A and C5A, in promoting inflammation, chemotaxis, and phagocytosis. The tutorial also covers how these components enhance the immune response by guiding white blood cells to infection sites and facilitating mast cell degranulation, which releases histamine to increase blood flow and vascular permeability.

What is the primary role of the B component in complement activation?

• To float away and signal other cells

• To degrade foreign material

• To act as a chemoattractant

• To bind to pathogens and form the membrane attack complex

Which anaphylatoxin is considered the strongest in terms of biological activity?

• C3A

• C3B

• C4A

• C5A

How do anaphylatoxins like C3A and C5A promote chemotaxis?

• By binding to pathogens directly

• By creating a concentration gradient that attracts white blood cells

• By degrading the pathogen

• By forming a physical barrier

What is the role of integrin in phagocytosis?

• To signal other immune cells

• To act as a chemoattractant

• To enhance the adherence of phagocytes to vessel walls

• To degrade pathogens

Which enzymes are upregulated by C3A and C5A to enhance phagocytosis?

• Protease enzymes

• Lipoxygenase pathway enzymes

• Amylase enzymes

• Nuclease enzymes

What effect does histamine have on blood vessels?

• It promotes vasodilation and increases vascular permeability

• It causes vasoconstriction

• It solidifies blood vessel walls

• It decreases vascular permeability

How do C3A and C5A contribute to inflammation?

• By forming a physical barrier

• By directly attacking pathogens

• By causing degranulation of mast cells and releasing histamine

• By acting as opsonins