Lecture 23- Immune/lymphatic Flashcards
Distinguish btw innate and acquired immunity
Innate:
lacks immune specificity and memory. Response = inflammation. Neutrophils are the first responders.
Acquired:
Develops in response to antigens. More powerful than innate immunity. Takes longer to develop. Displays specificity and memory.
Distinguish btw passive and active immunity.
Passive immunity:
Temporary immunity d/t donated antibodies (i.e., transplacental passing of maternal antibodies to fetus)
Active immunity:
Long-lasting/permanent immunity d/t self exposure to antigen resulting in memory T cells and B cells specific for antigen
Distinguish btw and identify primary and secondary immune tissue/organs.
Primary:
precursor cells mature into immunocompetent cells. Each programmed to recognize a specific antigen. In Thymus and bone marrow.
Secondary:
Trapped antigens stimulate clonal expansions of mature T and B cells. In lymph nodes, spleen, and tonsils.
*lymphocytes originate in primary organs then move to secondary
Describe distinguishing characteristics of a primary lymph follicle and compare w/ a secondary lymph follicle.
Lymph follicles: sites of B cell localization and proliferation.
Primary: spherical, tightly packed accumulations of virgin B cells and dendritic reticular cells that have not been exposed to antigens.
Secondary: Derived from primary follicles that have been exposed to nonself antigens. Aren’t present at birth.
Describe the function of the MHC and compare the 2 subdivisions of the MHC.
Major histocompatibility Complex function:presentation of antigenic peptides to T cells.
MHC I: expressed on the surface of ALL cells except trophoblast and RBCs
MHC II: Expressed on the surface of B cells and antigen-presenting cells
Compare characteristics of CD4+, CD8+, and CD16+ T cells.
CD4+ T cells: recognize antigens bound to MHC class II molecules—helper cells: assist CD8+ and B cell differentiation
CD8+ T cells: cytolytic T cells, bind to antigen presenting cell. Undergo mitosis. Release-perforins, Fas ligands. Recognize antigens bound to MHC class I molecules. Mediator of cellular immunity.
CD16+ T cells: Natural killer (NK) T cells. Activated (by tumor cell antigens) T-helper cells release cytokines.
Outline the interplay among T-helper cells, macrophages, B cells, and the MHC. In the immune response
Macrophages phagocytizes- it is broken bow into fragments-some of which are antigenic (epitopes).
Antigens are expressed on surface of macrophage bound to MHC-II.
MHC-II/antigen complex is presented to activated helper T cell.
Actvated T cell undergoes mitosis-DAUGHTERS BECOME MEMORY CELLS AND SOME SECRETE INTERLEUKINS->
T’s attract B cells. B’s have access to free antigens. B’s undergo mitosis.
–>SOME DAUGHTERS BECOME PLASMA CELLS(secrete antibodies) AND SOME BECOME MEMORY CELLS
Outline the steps in the complement cascade
Classic: cascade activated by antibody binding to pathogen.
Alternate: directly activated by the pathogen.
1. Antibody binds to C1q.
2.Activates C1r. Which then activates C1s.
3. C1s activates C4 and C2.
4. C4 activates c4a and c4b.
5. C2 activates c2a and c2b
6. C2b and C4b combine to a complex.
7. Via C3 convertase, C3 is formed and joins C4b-2b complex.
8. Via C5 convertase, 4b2b3b makes C5. C5 joins the 4b2b3b complex = forming 4b2b3b5b [final opsonization]
Name the most important opsonin
C3b
List the results of the complement cascade.
- activation of the membrane attack complex [MAC] on the pathogen leading to perforations and lysis.
- Production of opsonins, which are coatings that make the antigens more palatable to phagocytes.
- release of chemotactic agents (chemokines) which attract phagocytes (chemotaxis) to the areas of infection/inflammation.
Distinguish btw stroma and parenchyma
Stroma: consists mostly of reticular fibers and cells, including undifferentiated cells and fixed and free macrophages.
Parenchyma: consists of the cells that typically pack areas of the lymphoid organ-mostly lymphocytes.
List the distinguishing histological features of a lymph node, including differences among the outer cortex, inner cortex, and the medulla.
Hilus: entry and exit point for vessels.
Capsule: dense collagen fibers, some elastic fibers and smooth muscle fiber.
Outer cortex: contains lymph follicles (nodules)-follicles contain B cells, dendritic cells, germinal centers.
Inner cortex: Contains T-helper cells, macrophages, HEVs.
Medulla: irregular arrangement of loose medullary sinuses and dense medullary cords. Site of lymphocyte reentry into lymph stream. Thymic-dependent areas in subcortical and deeper medullary regions.
Describe the arrangement of lymph and blood vessels in r/t the lymph node.
Efferent lymphatic vessels as well as arteries and veins enter through hilus.
Lymph nodules (follicles) in outer cortex contain B cells
Describe the significance of HEVs
Port of entry for circulating differentiated lymphocytes to seed lymph node
Recognize lymph nodes in photomicrographs and important details
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