The video tutorial explains the complement system, a series of proteins in the blood that help defend against pathogens. It covers the conversion of C2 and C4 into C3, the roles of C3A and C3B in immune response, and the formation of the membrane attack complex (MAC) through the splitting of C5. Additionally, it discusses an alternate pathway that begins with C3 binding directly to pathogens. The tutorial emphasizes the importance of these processes in the body's defense mechanism.

What is the role of C3A in the complement system?

• It splits into C5A and C5B.

• It forms the membrane attack complex.

• It tags pathogens for destruction.

• It acts as a chemical attractant.

Which proteins are involved in forming the membrane attack complex?

• C5B and C6 through C9

• C5A and C5B

• C3A and C3B

• C1 to C3

What happens when C5 splits in the complement system?

• It forms C3A and C3B.

• It creates C5A and C5B.

• It interacts with factors PB and D.

• It binds directly to the pathogen.

How does the alternate pathway of the complement system begin?

• With C3 binding directly to the pathogen

• With C5 splitting into C5A and C5B

• With C1 binding to the pathogen

• With C3A attracting phagocytes

What is the function of the complement system in the body?

• To transport oxygen

• To produce hormones

• To defend against pathogens

• To digest food