Flashcards in Immunology Deck (59)
what are the functions of the lymphatic system?
drainage of tissue
absorption and transport of fatty acids and fats
what are the differences between lymphatic vessels and blood vessels?
lymphatic vessels are blind ended
cells that form lymph vessels are more delicate
what are the 3 phases of immune defence
recognition of danger
production of specific weapons
transport of weapons to site of attack
where are blood cells produced?
these are primary lymphoid organs
what is haematopoiesis?
formation and activation of blood cells
what is the function of the thymus?
"education" of T cells
what is the function of secondary lymphoid organs?
sites of lymphocyte activation by antigens
what 2 areas is the spleen divided into?
red pulp and white pulp
what is the function of the spleen?
filtration of blood
what separates red and white pulp?
what is a high endothelial venule?
simple columnar cells line venules, they are slightly looser than normal venules, which allows fluid and lymphocytes to leak out of the blood vessels.
what two zones are lymph nodes separated into?
B and T zones
what effect can T cells have on B cells?
they can cause B cells to produce antibodies
what are peyers patches?
patches of smooth cells embedded in villi covered cells.
what does MALT stand for?
mucosal associated lymphoid tissue
what covers peyers patches?
what is the difference between the adaptive and innate immune system?
adaptive is very specific and displays immunological memory
why does the adaptive immune system display a much larger response to an antigen in repeated exposure?
presence of memory cells allow a much quicker and stronger response after primary exposure
what are the differences between active and passive immunity?
active immunity - conferred by a host response to a microbe or a microbial antigen
passive immunity - conferred by adoptive transfer of antibodies or T lymphocytes specific for the microbe
active immunity is the only one that generates immunological memory
why does passive immunity not generate immunological memory?
because your own B cells are not involved in generating an immune response.
where are B cells produced?
what is the antigen receptor for a B cell
surface immunoglobulin (sIg)
why is it more important to tolerize T cells than B cells?
B cells cannot make antibodies in response to most antigens without the help of T cells
what is a pathogen?
any microorganism that causes disease.
what part of the pathogen are antibodies specific to?
what induces B cells to multiply?
recognition of a specific epitope on a specific antigen on a specific pathogen
what 2 chains are antibodies separated into?
light chain and heavy chain
what modification is made to antibodies after B cells multiply and produce them?
antibodies have a much higher affinity for epitope
what chain does the antibody bind to ?
what chain does the cell bind to?
what do the heavy chains define?
classes of immunoglobulin
how many different CLASSES of antibody are there?
(IGM IGD IGA IGE IGG)
what is the function of IGM
fixes compliment and opsonization
function of IGG
function of IGA
protects mucosal surfaces, resistant to stomach acid
function of IGE
defends against parasites, causes anaphylactic shock and allergies
what causes antibodies to be flexible?
presence of a hinge between the light and heavy chains
why does antigen bound iGm display good complement binding
binding to epitope causes a conformational change that allows c1 protein to bind to IgM
what is opsonisation
the process of "tagging" a pathogen which causes fc receptors to "stick up" which causes the pathogen to be more susceptible to phagocytic action
why do mast cells sometimes cause allergic reactions?
when mast cells encounter a pathogen they dump all of their contents onto the pathogen to neutralise it, and some of these molecules can cause allergic reaction in the host
what ways are there to activate a B cell?
T cell dependent
T cell independent
how does T cell dependent activation work?
Signal from a clustered BCR along with a signal from a T cell in which a protein on the surface of a T cell recognises the same antigen as the B cell and then binds to a receptor on the B cell
where do T cells go to get "educated"
what are T cells reponsible for?
cell mediated immunity and assisting B cells
what is the cell surface receptor of a T cell?
T cell receptor
what conditions have to be met in order for TCR to recognise antigens?
Has to be bound to MHC protein
What 2 classes of T cells are there?
helper (CD4+) and cytotoxic (CD8+)
what kind of antigens are T cells able to recognise?
ANY protein peptide that a pathogen may have due to association with MHC
What is it important for all lymphocytes to learn to do with regard to "self"
not to recognise "self" antigen
what happens to T cells that are unable to interact with MHC molecules
death by apoptosis
what determines what type of T cell thymocytes develop into?
whether it binds to MHC 1 (cytotoxic) or MHC 2 (helper)
what happens to T cells that cannot distinguish self from non self?
death by apoptosis
what is the purpose of MHC 1?
presents virally induced peptides to CD8+ T cells and trigger cytotoxic response
what is the purpose of MHC 2?
presents exogenously produced Ag to CD4+ T cells and activate macrophages and B cells
where is MHC 2 found?
on antigen presenting cells
what decides which T cell a naive T cell turns into after MHC peptide recognition?
range of different chemicals acting on T cells
Can T helper cells destroy pathogens?
what do cytotoxic T cells release once exposed to infected/dysfunctional somatic cells?
perforin, which forms pores in the target cell, also releases granzyme B - induces apoptosis