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Questions and Answers
Which pathway activates the complement system by binding to antibodies bound to antigens on the surface of microbes?
Which pathway activates the complement system by binding to antibodies bound to antigens on the surface of microbes?
What is the main function of the complement system in the immune system?
What is the main function of the complement system in the immune system?
How many biochemical pathways activate the complement system?
How many biochemical pathways activate the complement system?
What is the source of the proteins that make up the complement system?
What is the source of the proteins that make up the complement system?
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Which immune system component recruits and brings the complement system into action?
Which immune system component recruits and brings the complement system into action?
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What is the end result of the complement activation or complement fixation cascade?
What is the end result of the complement activation or complement fixation cascade?
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Which fragment of C2 was historically called C2a but is now referred to as C2b?
Which fragment of C2 was historically called C2a but is now referred to as C2b?
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What is the name of the classical pathway C3 convertase formed by the binding of C4b and C2b?
What is the name of the classical pathway C3 convertase formed by the binding of C4b and C2b?
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What activates the alternative pathway at a low level, analogous to a car engine at idle?
What activates the alternative pathway at a low level, analogous to a car engine at idle?
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Which factor rapidly inactivates C3b generated from C3 by a C3 convertase enzyme complex in the fluid phase?
Which factor rapidly inactivates C3b generated from C3 by a C3 convertase enzyme complex in the fluid phase?
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What prevents host cells from accumulating cell surface C3b and the proteolytic fragment of C3b called iC3b?
What prevents host cells from accumulating cell surface C3b and the proteolytic fragment of C3b called iC3b?
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What is the name of the complex formed by the binding of factor B to surface-bound C3b in the alternative complement pathway?
What is the name of the complex formed by the binding of factor B to surface-bound C3b in the alternative complement pathway?
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What stabilizes the C3 convertase C3bBb complex in the alternative complement pathway?
What stabilizes the C3 convertase C3bBb complex in the alternative complement pathway?
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What greatly amplifies the complement activation in the alternative complement pathway?
What greatly amplifies the complement activation in the alternative complement pathway?
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Which pathway is the primary driver of terminal pathway activation in the complement system?
Which pathway is the primary driver of terminal pathway activation in the complement system?
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Who discovered mild killing activity in sheep blood serum against anthrax in 1888?
Who discovered mild killing activity in sheep blood serum against anthrax in 1888?
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What did Jules Bordet identify as two components in the killing property named 'alexin'?
What did Jules Bordet identify as two components in the killing property named 'alexin'?
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Who renamed the heat-sensitive component 'complement' in 1899 as part of his theory of the immune system?
Who renamed the heat-sensitive component 'complement' in 1899 as part of his theory of the immune system?
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Which component of the complement system triggers membrane attack, phagocytosis, and inflammation?
Which component of the complement system triggers membrane attack, phagocytosis, and inflammation?
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What is the key protease in all three pathways of the complement system?
What is the key protease in all three pathways of the complement system?
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Which pathway of the complement system is activated by binding to antibodies bound to antigens on the surface of microbes?
Which pathway of the complement system is activated by binding to antibodies bound to antigens on the surface of microbes?
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What is the name of the complex formed by the binding of factor B to surface-bound C3b in the alternative complement pathway?
What is the name of the complex formed by the binding of factor B to surface-bound C3b in the alternative complement pathway?
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Which factor rapidly inactivates C3b generated from C3 by a C3 convertase enzyme complex in the fluid phase?
Which factor rapidly inactivates C3b generated from C3 by a C3 convertase enzyme complex in the fluid phase?
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Who discovered mild killing activity in sheep blood serum against anthrax in 1888?
Who discovered mild killing activity in sheep blood serum against anthrax in 1888?
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What is the main function of the complement system in the immune system?
What is the main function of the complement system in the immune system?
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What enhances the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism?
What enhances the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism?
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Which of the following components is responsible for triggering degranulation of mast cells and increasing vascular permeability and smooth muscle contraction in the complement system?
Which of the following components is responsible for triggering degranulation of mast cells and increasing vascular permeability and smooth muscle contraction in the complement system?
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What is the name of the complex formed by the binding of factor B to surface-bound C3b in the alternative complement pathway?
What is the name of the complex formed by the binding of factor B to surface-bound C3b in the alternative complement pathway?
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Which pathway in the complement system can be activated without the presence of antibodies?
Which pathway in the complement system can be activated without the presence of antibodies?
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What is the primary driver of terminal pathway activation in the complement system?
What is the primary driver of terminal pathway activation in the complement system?
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Who initially discovered mild killing activity in sheep blood serum against anthrax?
Who initially discovered mild killing activity in sheep blood serum against anthrax?
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What did Paul Ehrlich rename the heat-sensitive component to in 1899 as part of his theory of the immune system?
What did Paul Ehrlich rename the heat-sensitive component to in 1899 as part of his theory of the immune system?
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What is the name of the complex formed by the binding of factor B to surface-bound C3b in the alternative complement pathway?
What is the name of the complex formed by the binding of factor B to surface-bound C3b in the alternative complement pathway?
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What is the primary driver of terminal pathway activation in the complement system?
What is the primary driver of terminal pathway activation in the complement system?
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What stabilizes the C3 convertase C3bBb complex in the alternative complement pathway?
What stabilizes the C3 convertase C3bBb complex in the alternative complement pathway?
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Which pathway in the complement system can be activated without the presence of antibodies?
Which pathway in the complement system can be activated without the presence of antibodies?
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What prevents host cells from accumulating cell surface C3b and the proteolytic fragment of C3b called iC3b?
What prevents host cells from accumulating cell surface C3b and the proteolytic fragment of C3b called iC3b?
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Which fragment of C2 was historically called C2a but is now referred to as C2b?
Which fragment of C2 was historically called C2a but is now referred to as C2b?
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What activates the alternative pathway at a low level, analogous to a car engine at idle?
What activates the alternative pathway at a low level, analogous to a car engine at idle?
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What greatly amplifies the complement activation in the alternative complement pathway?
What greatly amplifies the complement activation in the alternative complement pathway?
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What is the name of the complex formed by the binding of factor B to surface-bound C3b in the alternative complement pathway?
What is the name of the complex formed by the binding of factor B to surface-bound C3b in the alternative complement pathway?
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What is the end result of the complement activation or complement fixation cascade?
What is the end result of the complement activation or complement fixation cascade?
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What stabilizes the C3 convertase C3bBb complex in the alternative complement pathway?
What stabilizes the C3 convertase C3bBb complex in the alternative complement pathway?
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What prevents host cells from accumulating cell surface C3b and the proteolytic fragment of C3b called iC3b?
What prevents host cells from accumulating cell surface C3b and the proteolytic fragment of C3b called iC3b?
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What activates the alternative pathway at a low level, analogous to a car engine at idle?
What activates the alternative pathway at a low level, analogous to a car engine at idle?
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Which component of the complement system triggers membrane attack, phagocytosis, and inflammation?
Which component of the complement system triggers membrane attack, phagocytosis, and inflammation?
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What is the name of the classical pathway C3 convertase formed by the binding of C4b and C2b?
What is the name of the classical pathway C3 convertase formed by the binding of C4b and C2b?
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What is the main function of the complement system in the immune system?
What is the main function of the complement system in the immune system?
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Study Notes
Complement System Overview
- The alternative pathway is the primary driver of terminal pathway activation, and therapeutic efforts in disease have centered on its inhibition.
- In 1888, George Nuttall discovered mild killing activity in sheep blood serum against anthrax, which disappeared upon heating.
- In 1891, Hans Buchner named this killing property "alexin" and Jules Bordet identified two components: a heat-stable sensitizing effect and a heat-sensitive toxic effect.
- Paul Ehrlich renamed the heat-sensitive component "complement" in 1899 as part of his theory of the immune system.
- Complement consists of proteins and glycoproteins synthesized by hepatocytes and various cells, and has three pathways of activation.
- The classical pathway requires antigen-antibody complexes, the alternative pathway can be activated spontaneously, and the lectin pathway can be activated without the presence of antibodies.
- Complement triggers immune functions including membrane attack, phagocytosis, and inflammation.
- C3-convertase is a key protease in all three pathways, cleaving and activating component C3 to create C3a and C3b, leading to a cascade of further cleavage and activation events.
- C3b binds to pathogens, leading to greater internalization by phagocytic cells in the alternative pathway.
- C5a and C3a have anaphylatoxin activity, triggering degranulation of mast cells and increasing vascular permeability and smooth muscle contraction.
- C5b initiates the membrane attack pathway, resulting in the membrane attack complex (MAC) and causing osmotic lysis of the target cell.
- The classical pathway is triggered by activation of the C1-complex, composed of C1q, C1r, and C1s, when C1q binds to IgM or IgG complexed with antigens or directly to the pathogen's surface.
Complement System Overview
- The alternative pathway is the primary driver of terminal pathway activation, and therapeutic efforts in disease have centered on its inhibition.
- In 1888, George Nuttall discovered mild killing activity in sheep blood serum against anthrax, which disappeared upon heating.
- In 1891, Hans Buchner named this killing property "alexin" and Jules Bordet identified two components: a heat-stable sensitizing effect and a heat-sensitive toxic effect.
- Paul Ehrlich renamed the heat-sensitive component "complement" in 1899 as part of his theory of the immune system.
- Complement consists of proteins and glycoproteins synthesized by hepatocytes and various cells, and has three pathways of activation.
- The classical pathway requires antigen-antibody complexes, the alternative pathway can be activated spontaneously, and the lectin pathway can be activated without the presence of antibodies.
- Complement triggers immune functions including membrane attack, phagocytosis, and inflammation.
- C3-convertase is a key protease in all three pathways, cleaving and activating component C3 to create C3a and C3b, leading to a cascade of further cleavage and activation events.
- C3b binds to pathogens, leading to greater internalization by phagocytic cells in the alternative pathway.
- C5a and C3a have anaphylatoxin activity, triggering degranulation of mast cells and increasing vascular permeability and smooth muscle contraction.
- C5b initiates the membrane attack pathway, resulting in the membrane attack complex (MAC) and causing osmotic lysis of the target cell.
- The classical pathway is triggered by activation of the C1-complex, composed of C1q, C1r, and C1s, when C1q binds to IgM or IgG complexed with antigens or directly to the pathogen's surface.
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Description
Test your knowledge of the complement system with this quiz. Explore the pathways of activation, key components, and immune functions triggered by complement. Dive into the history of its discovery and its role in disease therapy.
