Physiology of the Immune System III and IV Practise
Questions
1. What are the three pathways that make up the complement cascade?: clas- sical pathway, lectin
pathway, and the alternative pathway
2. Describe the classical pathwawy: THe classical pathway deals with C1 binding to form the
antibody-antigen complexes and it occurs in certain virons/ infected cells
Basically in this pathway the C1 is activated by vertain virions and infectedcells which results in
the activation of C1 which binds to C4 and activates it. The C4 can be broken down into C4B and
C4A and it is the C4B that can cause the activation of C3 via C3 convertase.
3. Describe the lectin pathway: It requires mannan-binding lectins (MBL) for acti- vation. Once the
MBL binds to an oligosaccharide on different pathogens it causes the activation of C4 which
converts C4 into C4b and C4a. Same as the classical pathway, the C4b can then coalesce wtih
C2 and acitvates C3 enzyme convertase
4. Describe the alternative pathway: Deals with the spontaneous breakdown of C3 by a pathogen
or antigen in the serum. Once its randombly activatived the result is a huge complex that is an
alternative form. to C4 and then can activate an alternative C3 convertase
5. What happens once all the pathways (alternative, classical, and lectin) converge =?: One they
converge it activates C3 convertase which activates C3. C3 binds to C5 convertase through
various steps forming C6-C9. In the end is the creation of the Membrane Attack Complex.
6. Describe the formation of the complement: Membrane Attack Complex.: So once C3b is activates
it activates C5 which releases C5(a)-pro-inflammatory cy- tokine! it also Release C5b which can
then bind onto the cell membrane and recruits C6, C7, C8,an ad C9. It gets multiples of the large
C9 and forms a pore that can have is diameter increases and then microbes can go into it and
cause lysis.
7. What is the alternative pathways activated by: -microbial cell membrane (bac- teria, fungi)
-insects (esoskeleleton)
8. What is the rate of the alternative pathway?: Activation is slower, less active, and it responds to
general stimuli
9. What is the classical pathway of the complement activated by?: -Im- munoglobulins
(igM, IgG)-antibodies
-Haegeman factor (facotro XIII, blood coagulation factor)
-C reactive protein (acute phase )
10.What is the rate of the classical pathway?: activation is quick, it is very active, and it responds
to far more specific stimuli
11.What are some of the results of the complement pathway?: -chemotaxis
-phagocyte activation
For assistance with assignments contact
, Physiology of the Immune System III and IV Practise
Questions
12.Describe complement-chemotaxis?: This is when leukocytes move towards a chemical
mediator such as a bacterial cell wall, eiconasoids (leukotriene), cy- tookines.
13.What does chemotaxis result in?: It results in the recruitment of the white blood cells out
of the cell.
14.What are the phagocytic leukocytes?: neutrophils and macrophages
15.When do phagocytes become activated as it relates to the complement process?: The
phagocytic leukocytes become more active and more able to kill microbes when they are
activated by exposure to complements fragments such as C3a,C4a, and C5a (which are some of
the byproducts in the complement cascade.
16.What does phagocyte activation cause?: -release of ROS like H2O2 (perox- ide)-which
enhances microbial killing and injury to tissue cells
-release mediators ie cytokines-cause activation of other leukocytess.
-release of histamines (and other mediators from mast cells)
17.Summarize the complement functions.: So the alternative and classical path- ways targeting a
microbe converge and cause C3b to be deposite on a microbe.
-Once C3b is activated it can cause a variety of things including:
-causing C3A and C5A to recruit WBC's and cause inflammation by destroying the microbes
-C3b can do phagocytosis and be recognized by the phagocyte C3b receptor resulting in
phagocytosis
-Or C3b can go and form the MAC complex which causes the lysis of a microbe
18.What is the life span of the complement components?: sharot half life due to rapid inaction by
several plasma inhibitors.
19.What are the plasma inhibitors that help regulate the formation of the complements?: -C1
inhibitor
-Protein S (anticlotting protein)
-others
20.Classical Pathway (shortened definition): -Microbes has antigen
-IGE (antibody) binds to the antigen forming the antigen-antibody complex.
-This complex then attract C1 out of the blood.
-C1 binds to immune complex activating C4 and conversion of C4 to C4b and C4a.
-C4B can go on to activate C3 convertase
For assistance with assignments contact
Questions
1. What are the three pathways that make up the complement cascade?: clas- sical pathway, lectin
pathway, and the alternative pathway
2. Describe the classical pathwawy: THe classical pathway deals with C1 binding to form the
antibody-antigen complexes and it occurs in certain virons/ infected cells
Basically in this pathway the C1 is activated by vertain virions and infectedcells which results in
the activation of C1 which binds to C4 and activates it. The C4 can be broken down into C4B and
C4A and it is the C4B that can cause the activation of C3 via C3 convertase.
3. Describe the lectin pathway: It requires mannan-binding lectins (MBL) for acti- vation. Once the
MBL binds to an oligosaccharide on different pathogens it causes the activation of C4 which
converts C4 into C4b and C4a. Same as the classical pathway, the C4b can then coalesce wtih
C2 and acitvates C3 enzyme convertase
4. Describe the alternative pathway: Deals with the spontaneous breakdown of C3 by a pathogen
or antigen in the serum. Once its randombly activatived the result is a huge complex that is an
alternative form. to C4 and then can activate an alternative C3 convertase
5. What happens once all the pathways (alternative, classical, and lectin) converge =?: One they
converge it activates C3 convertase which activates C3. C3 binds to C5 convertase through
various steps forming C6-C9. In the end is the creation of the Membrane Attack Complex.
6. Describe the formation of the complement: Membrane Attack Complex.: So once C3b is activates
it activates C5 which releases C5(a)-pro-inflammatory cy- tokine! it also Release C5b which can
then bind onto the cell membrane and recruits C6, C7, C8,an ad C9. It gets multiples of the large
C9 and forms a pore that can have is diameter increases and then microbes can go into it and
cause lysis.
7. What is the alternative pathways activated by: -microbial cell membrane (bac- teria, fungi)
-insects (esoskeleleton)
8. What is the rate of the alternative pathway?: Activation is slower, less active, and it responds to
general stimuli
9. What is the classical pathway of the complement activated by?: -Im- munoglobulins
(igM, IgG)-antibodies
-Haegeman factor (facotro XIII, blood coagulation factor)
-C reactive protein (acute phase )
10.What is the rate of the classical pathway?: activation is quick, it is very active, and it responds
to far more specific stimuli
11.What are some of the results of the complement pathway?: -chemotaxis
-phagocyte activation
For assistance with assignments contact
, Physiology of the Immune System III and IV Practise
Questions
12.Describe complement-chemotaxis?: This is when leukocytes move towards a chemical
mediator such as a bacterial cell wall, eiconasoids (leukotriene), cy- tookines.
13.What does chemotaxis result in?: It results in the recruitment of the white blood cells out
of the cell.
14.What are the phagocytic leukocytes?: neutrophils and macrophages
15.When do phagocytes become activated as it relates to the complement process?: The
phagocytic leukocytes become more active and more able to kill microbes when they are
activated by exposure to complements fragments such as C3a,C4a, and C5a (which are some of
the byproducts in the complement cascade.
16.What does phagocyte activation cause?: -release of ROS like H2O2 (perox- ide)-which
enhances microbial killing and injury to tissue cells
-release mediators ie cytokines-cause activation of other leukocytess.
-release of histamines (and other mediators from mast cells)
17.Summarize the complement functions.: So the alternative and classical path- ways targeting a
microbe converge and cause C3b to be deposite on a microbe.
-Once C3b is activated it can cause a variety of things including:
-causing C3A and C5A to recruit WBC's and cause inflammation by destroying the microbes
-C3b can do phagocytosis and be recognized by the phagocyte C3b receptor resulting in
phagocytosis
-Or C3b can go and form the MAC complex which causes the lysis of a microbe
18.What is the life span of the complement components?: sharot half life due to rapid inaction by
several plasma inhibitors.
19.What are the plasma inhibitors that help regulate the formation of the complements?: -C1
inhibitor
-Protein S (anticlotting protein)
-others
20.Classical Pathway (shortened definition): -Microbes has antigen
-IGE (antibody) binds to the antigen forming the antigen-antibody complex.
-This complex then attract C1 out of the blood.
-C1 binds to immune complex activating C4 and conversion of C4 to C4b and C4a.
-C4B can go on to activate C3 convertase
For assistance with assignments contact
