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44 Cards in this Set
- Front
- Back
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Circulation of lymph
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blood capillaries-> tissue-> some into lymph-> lymph nodes-> thoracic duct-> venous blood circulation
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List the 4 major types of lymphoid tissue
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-diffuse lymphoid tissue
-lymph nodule -lymph node and spleen (true organs) -bone marrow and thymus |
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Describe diffuse lymphoid tissue
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Loose collection of lymphocytes , often in connective tissue underlying epithelia that are involved in transport of materials from outside world
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Describe lymph nodules
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lymphocytes organized in germinal center (growth center for B cells)
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germinal center
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where B cell clones grow
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True lymph organs
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Lymph node and spleen. Have capsule, arteries and veins. Contain lymph nodules
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Sites of lymphocyte production and maturation
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Bone marrow and thymus
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Lymphocyte precursors are generated in the ______________ from _______________ cells
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bone marrow; hematopoietic
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Cells of the Immune response:
3 primary 5 accessory |
Lymphocytes:
-B cells - cell free and plasma membrane bound antigens (humoral response) -T cells - respond to cell-bound antigens -Helper T cells (CD4+), cytolytic T cells (CD8+) -Natural killer cells -Macrophages/Dendritic Cells -Mast cells, Eosinophils, Basophils B cells |
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thymus is compartmentalized by ________ cells
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epithelial
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Hassall's corpuscle
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onion-like epithelial cells found in medulla of thymus. More and bigger in older people. histological marker for thymus
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blood-thymus barrier
INCOMPLETE |
TBA
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Where are B cells found in lymph nodules? T cells?
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B cells in cortex; T cells in paracortex
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Where are plasma cells and macrophages found in lymph nodes
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Medullary cords (macrophages are also in lymph-filled sinuses
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Where do B cell precursors differentiate?
Where do they go after they differentiate? |
-Marrow
-To lymphoid tissue via blood |
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how do B cells recognize proteins (term)
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Addressins: venule epithelium ligands that determine lymph destination
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high endothelial venules
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venules with roughly cuboidal endothelium. B cells leave from blood here
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White pulp
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lymphoid tissue in the spleen.
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Functions of spleen
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-primary filter for foreign materials
-RBC destruction |
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red pulp
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region where RBC's are being selected for destruction
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the body's 3 main lines of defense against infection
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-protective surface mechanisms (eg. mucous, cilia)
-non-specific (innate) tissue defense (neutrophils, etc) -specific immune responses (T cell/B cell) |
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Discuss 1st step of immune response: activation of helper cell by phagocytic cell
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-Phagocytic cell phagocytizes pathogen
-Cell displays pathogen antigen (pieces of cell) on cell surface -Helper T's (or cytolytic T's) recognize antigen and are activated |
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humoral immunity
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B cell is activated by activated T cell (helper T cell?) and proliferates. Most cells become plasma cells and produce antibodies. Some become (resting) memory cells to respond quickly to future infections.
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What happens after T cell is activated (roughly)
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-activation of helper T
- "clonal expansion" of helper T cells (mitosis) -helper T interacts with B cells -B cell proliferates into memory cells or plasma cells |
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Discuss Killer T's
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cell-mediated immunity
-are activated by antigen presenting cell -proliferate, find infected cells -kill cell -DOES NOT trigger humoral immunity! |
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4 main functions of immune system
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-generate immunocompetent lymphocytes
-concentrate antigens in specific tissues -circulate lymphocytes -deliver antibodies and effector T-cells |
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primary lymphatic tissue
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bone marrow, thymus. Where cells originate and mature
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Where are B cells produced? T cells?
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Both are produced (originally) in bone marrow
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Where do B cells mature? T cells?
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B cells in marrow. T cells in thymus
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Where is the thymus located
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Upper mediastinum, but probably not visible in our cadavers
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Thymus: Basic structure
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-thin connective tissue capsule w/ 2 parts:
-cortex -medulla -highly lobulated |
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Path of T cell through thymus
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-immature T cells enter cortex with no markers (CD4, CD8)
-Cells develop BOTH markers as they move toward the medulla -Cells lose on marker -if cells do not lose a marker or if they have "self" designating antigens, they will undergo apoptosis (macroghages ingest remains) -Mature, specific T cells exit cortex into medulla |
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Secondary lymphatic tissue (3)
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-Non-encapsulated Aggregates
-Lymph Nodes -Spleen Residences of mature lymphocyes (?) |
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Lymph follicle
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collection of B cells, found in cortex of lymph nodes
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Structures of a lymph node.
What does blood do when it enters a lymph node? |
cortex: follicles - collections of B cells, and paracortex - lots of T-cells
medulla Blood enters, percolates, leaves. |
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Whitish spot within a follicle
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germinal center. Immune response has been initiated and B cells are undergoing mitosis
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Chain reaction when antigen enters lymph node
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Antigen is picked up by antigen presenting cell -> activates T -> T activates Bs
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Do Bs and Ts always stay in a certain lymph node?
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No, if they haven't been activated in a while they can wander out in the blood and enter general circulation
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Medullary sinus
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in lymph nodes (and others?). Space that the lymph flows through
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medullary cords
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cords inside sinuses which macrophages and plasma cells hang onto.
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What is special about the endothelium of lymph nodes
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the cells are more cuboidal than normal simple squamous. Lymphocytes see the tissue and know they are at a lymph node and leave the blood.
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Basic function of lymph node
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to aggregate antigens and immune defence cells (B, T, antigen presenting)
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2 divisions in the spleen
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white pulp - lymphocytes
red pulp - RBCs, macrophages, and everything else with the blood |
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PALS (slide 18)
Incomplete |
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