2: Cells and tissues of the immune system Flashcards
what happens to eosinophils after leaving bone marrow
migrate to the spleen where they mature, then migrate into tissues
what are eosinophils responsible for (3)
- phagocytosis and killing of parasites
- Fc receptors on surface to bind antibodies
- produce cytokines
what do eosinophilic granules contain (3)
- phosphatase
- peroxidase
- toxic proteins
what do basophil granules contain
inflammatory molecules (histamine, serotonin)
what do basophils do
play a role in killing of parasites due to presence of FceRI
what do mast cells do
play a role in killing of parasites due to presence of FceRI
what do mast cell granules contain
vasoactive amines (histamine, serotonin)
what is adaptive immune response mediated by
lymphocytes
what is adaptive immunity specific to
a given molecule (epitope –> 8-12 amino acids)
what does adaptive immune system do (3)
- has surface receptors for antigens on pathogens or particles
- provides specific immunity to antigens
- provides memory of specific antigens
what do b cells do (3)
- produce antibodies
- antibodies bind antigens
- antibodies interact with components of the innate immune system
what do t cells do (3)
- recognize processed antigen on host cells (cell mediated immunity)
- helper t cells activate or regulate activities of other cells
- cytotoxic t cells kill host cells bearing a foreign antigen
what is clonal selection
lymphocytes undergo clonal selection based on an individual cell having the correct receptor for a very small, defined part of a larger antigen
what happens to lymphocyte receptors
genome rearranges randomly at the site where the receptors are encoded –> generates cells of the same type but with different receptors
what do lymphoid organs have sites for
- sites where lymphocytes develop and/or contact and respond to specific antigens
- points of differentiation, antigen and immune cell collection, and adaptive immune responses
places of differentiation and activation
- differentiation: primary organ
- activation: secondary organ
what are primary lymphoid organs sites of
production and differentiation for lymphocytes
examples of primary lymphoid organs
- bone marrow or bursa of fabricus (avian): b cells
- thymus: t cells
- peyers patches: b cells (especially ruminants)
what are 2 primary organs that are also secondary
bone marrow, bursae
what can serve as sites for lymphoid production when excessive blood cell production is demanded
liver and spleen
what are supporting cells in bone marrow and what do they support
stromal cells –> lymphopoiesis and myelopoiesis
what are peyers patches
structures located along the gastrointestinal tract within the lamina propria
what do peyers patches contain
large numbers of lymphocytes, mostly b cells
how are peyers patches arranged
arranged in follicles with b cells central and t cells surrounding them
what are peyers patches important for
- immune responses for ingested antigens
- sites of primary b cell differentiation
what do peyers patches do
take up antigen from the gut and transport it to draining lymph nodes
what are secondary lymphoid organs (definition)
sites where lymphocytes develop and/or contact and respond to specific antigens (collection and response points)
examples of secondary lymphoid organs (5)
- SPLEEN
- LYMPH NODES
- tonsils
- peyers patches
- bone marrow
2 parts of spleen and their functions
- red pulp contains phagocytes
- white pulp contains lymphocytes, mostly B cells but also T cells
2 components of white pulp in spleen
- splenic nodules (contain b lymphocytes)
- periarterial lymphatic sheaths (t-lymphocytes)
what is the largest lymphoid organ
spleen
what is the spleen the major site of
adaptive immune responses to blood-borne pathogens (filters out effete red blood cells)
what are lymph nodes points of
convergence for cells in the blood and lymph systems
what do lymph nodes collct
extracellular fluid (lymph) from tissues for return to the blood
what do lymph nodes contain
b and t cells in segregated regions
what causes swollen lymph nodes
b cell proliferation in germinal centers
what do somatic mutations in germinal centers do
help with adaptive immune response
what is lymph node divided into
- outer cortex
- inner medulla
- surrounded by a capsule
where do most lymphocytes migrating to lymph nodes enter from
peripheral blood
what can only lymphocytes interact with and exravasate through
high endothelial venules (HEVs) to migrate into lymph node parenchyma
what are high endothelial venules (HEVs)
-specialized capillaries of lymphoid tissues where lymphocytes exchange from the blood
what do endothelial cells in the HEV lack
tight junctions
