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163 Cards in this Set
- Front
- Back
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what are the organs involved in the immune system?
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thymus
spleen tonsils bone marrow lymph nodes |
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what type of blood cells are involved in the immune system?
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leukocytes
(T cells, B cells, macrophages) |
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where is diffuse lymphatic tissue prominent?
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loose connective tissue
(beneath epithelia lining body cavities) |
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what layer of tissue contains diffuse lymphatic tissue?
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lamina propia beneath mucosa
(GI tract, Respiratory tract) |
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how is diffuse lymphatic tissue organized?
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loose clusters of immune cells
(lymphatic nodules) |
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which lymphocytes are predominant in lymphoid (lymphatic) nodules?
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B cells
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what are the types of lymphoid nodules?
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primary
secondary |
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what distinguishing feature do some lymphoid nodules have?
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germinal center (secondary nodules)
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which type of lymphoid nodules have germinal centers?
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secondary nodules
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how does a germinal center appear?
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centralized, lightly staining, surrounded by dark-staining sphere
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what is the germinal center composed of?
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lymphoblasts
B cells |
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what happens to B cells in the germinal center of a lymphoid nodule?
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proliferates and differentiates into plasma cells
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what are Peyer's patches?
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clusters or aggregates of lymphatic nodules in the ileum
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where are Peyer's patches located?
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in the ileum
(last part of the small intestine) |
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Peyer's patches are components of what tissue system?
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gut-associated lymphatic tissue (GALT)
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in H&E stain, what color does the cortex of the thymus stain?
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dark
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in H&E stain, what color does the medulla of the thymus stain?
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light
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where are the lymphoid nodules located in the thymus?
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there are none
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what extends into the thymus as septa, dividing it into incomplete lobules?
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connective tissue capsule of the thymus
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what type of lymphocytes are contained in the thymus?
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T cell and T lymphocyte precursors
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where are T lymphocytes derived from?
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stem cells in bone marrow
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where do T lymphocytes proliferate and mature?
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thymus
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what type of T cell precursors enter the thymus?
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double-negative cells
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what type of T cell precursors are in the subcapsular cortex of the thymus?
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double-negative cells
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what type of T cell precursors are seen in the deep cortex of the thymus?
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double-positive cells
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what type of T cells are seen in the medulla?
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mature T cells
aka single-positive T cells |
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which pharyngeal pouches are responsible for the development of the thymus?
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3rd and sometimes 4th
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what type of embryonic tissue(s) is the thymus derived from?
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endoderm
mesoderm ectoderm |
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what parts of the thymus are developed from endoderm?
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medullary epithelial reticular cells
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what parts of the thymus are developed from ectoderm?
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cortical epithelial reticular cells
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what parts of the thymus are derived from mesoderm?
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thymocytes
connective tissue capsule |
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what are the components of the capsule called which extend into the thymus? what effect does this have?
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trabeculae
divides the thymus into incomplete lobules |
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what happens to the thymus at puberty?
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involutes
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what does involution involve?
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slowed proliferation of thymocytes
shrinkage of thymic cortex increase in number of Hassal's corpuscles |
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what replaces active thymic tissue during involution?
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connective tissue
adipose tissue |
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where is the site of the blood-thymus barrier?
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cortex of the thymus
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what is the name of the division between the cortex and the medulla of the thymus?
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corticomedullary junction
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what are thymocytes?
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immature T lymphocytes
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what supports thymocytes in the thymus?
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meshwork of epithelial reticular cell processes
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what is absent in the thymus which is different from other lymphoid organs?
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reticular cells or fibers
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how are epithelial reticular cells in the thymus connected?
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tight junctions
desmosomes |
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what is the name for the abundant intermediate filaments which anchor desmosomes to cytoskeleton in epithelial reticular cells?
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tonofilaments
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what forms the blood-thymus barrier?
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continuous blood capillaries in thymic cortex
reinforced by epithelial reticular cells and macrophages |
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what type of cells are "nurse cells" a subpopulation of?
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epithelial reticular cells
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what is the function of nurse cells?
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enclose thymocytes in cytoplasm
secrete substances to promote thymocyte development |
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what is a common substance secreted by nurse cells to promote thymocyte development?
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colony stimulating factors
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what is another name for mature T cells?
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immunocompetent T cells
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where do mature T cells enter the blood stream?
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through walls of postcapillary venules in the cortex
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what staining property does the thymic medulla have?
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acidophillic (light staining)
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what staining property does the thymic cortex have?
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basophillic (dark-staining)
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where are Hassall's corpuscles found?
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thymic medulla
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what do Hassal's corpuscles consist of?
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concentric layers of flattened epithelial reticular cells
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what part of a Hassall's corpuscle may be keratinized?
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center
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what are the three "layers" of the blood-thymus barrier?
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continuous capillaries
macrophages epithelial reticular cells |
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what is the purpose of the blood-thymus barrier?
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prevents antigenic material from reaching thymocytes
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what is the purpose of the continuous capillaries in the thymic cortex?
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limit what can enter the thymic tissue
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what surrounds continuous capillaries in the thymic cortex?
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basal lamina
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where are the macrophages located that are important in the blood-thymus barrier?
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in perivascular connective tissue between capillary wall and layer of epithelial reticular cells
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what causes DiGeorge syndrome?
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deletion of small piece of chromosome 22
third and fourth pharyngeal pouches don't develop, which causes small or nonexistent thymus and parathyroid glands |
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which thymocytes are affected (deficient or nonexistent) in individuals with DiGeorge syndrome?
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T cells
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what is the mnemonic for symptoms in DiGeorge syndrome? what does it stand for?
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CATCH22
C- cardiac abnormality A- abnormal facies T- thymic aplasia C- cleft palate H- hypocalcemia 22- chromosome 22 |
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what disorder has symptomatic tetany associated with it?
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DiGeorge syndrome
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what is symptomatic tetany?
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a type of seizure caused by the hypocalcemia associated with DiGeorge syndrome
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what are the functions of lymph nodes?
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filter lymph
maintain and produce T- and B- lymphocytes store memory cells |
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what are the important parts of lymph nodes?
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cortex (superficial and deep)
medulla lymphatic vessels sinuses |
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what surrounds lymph nodes?
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capsule of dense connective tissue
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what are the extensions of the capsule of lymph nodes called?
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trabeculae
(extend into the parenchyma) |
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where are the afferent lymphatic vessels received in a lymph node?
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the convex surface
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where do arterioles enter lymph nodes?
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concave surface (aka hilum)
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where do efferent lymphatic vessels exit lymph nodes?
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concave surface (aka hilum)
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where do venous vessels exit lymph nodes?
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concave surface (aka hilum)
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what is the stroma of a lymph node?
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supportive framework
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what is rich in the stroma of a lymph node?
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reticular fibers
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what is between the superficial cortex and the capsule of a lymph node?
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subcapsular sinus
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what occurs in the germinal center of a lymphoid nodule?
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B cell mitosis and proliferation
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what type of lymphocyte is prevalent in the deep cortex?
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T cells
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what type of lymphocyte is prevalent in the superficial cortex?
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B cells
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what are contained in the sinuses of lymph nodes?
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reticular fibers
reticular cells macrophages |
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what occurs in the sinuses of lymph nodes?
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lymph filtration
traps antigenic material and tumor cells mechanically phagocytosis of captured material by macrophages |
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how wide is the meshwork of cells and cell processes in the subcapsular sinus?
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spans width of subcapsular sinus
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what is another name for the deep cortex of a lymph node?
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paracortical zone
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what type of lymphocyte is predominant in the paracortical zone?
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T-cells
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how do the large majority of T cells enter lymph node cortex?
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through high-endothelial cells along postcapillary venules in paracortical zone
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what is distinctive about high-endothelial venules?
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nuclei protrude into lumen of vessel
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what is the medulla of a lymph node composed of?
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medullary cords
medullary sinuses |
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what is contained within medullary cords and sinuses?
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reticular cells
reticular fibers macrophages dendritic cells plasma cells lymphocytes |
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what type of lymphocyte predominates in the medulla?
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B lymphocytes
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what type of cell is common in the medullary cords of a lymph node?
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plasma cells
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which lymphatic vessels are present in lymph nodes? which have valves?
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afferent lymphatic vessels
efferent lymphatic vessels both have valves |
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what is the purpose of afferent lymphatic vessels?
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deliver lymph to node
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what is the purpose of efferent lymphatic vessels?
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carry lymph away from node
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what type of blood cells are present in lymph? which are not present in lymph?
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white blood cells
red blood cells |
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what cells in lymph nodes remove cellular debris and antigens carried by lymph?
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macrophages
dendritic cells |
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what stimulates T cells to undergo transformation, clonal expansion, and then differentiation into effector or memory cells?
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presentation of antigen by macrophages or dendritic cells (in lymph nodes or tissue)
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what stimulates B cells to move to germinal centers to undergo blast formation, clonal expansion, and differentiation into memory or plasma cells?
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antigen presentation by macrophages or dendritic cells
release of cytokines from helper T cells |
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what cells are responsible for secreting immunoglobulins into lymph? where do many of them reside?
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plasma cells
medullary cords |
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In spleen, what is the white pulp?
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lymphoid nodules
pale |
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In spleen, what is the red pulp?
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erythrocyte-rich tissue
red |
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when stained with H&E, what color do lymphoid nodules stain?
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blue-purple
(basophilic) |
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structurally, how is the spleen different from the thymus and the lymph nodes?
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lacks a cortex and medulla
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what is the name for extensions of the capsule of the spleen into the parenchyma of the spleen?
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trabeculae
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what forms the structural framework of the spleen?
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reticular fibers
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where do reticular fibers run in the spleen?
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extend along trabeculae
extend around splenic blood vessels |
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where is the hilum of the spleen located?
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medial surface
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what enters/leaves the spleen through the hilus?
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nerves
blood vessels |
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where is all of the spleen's lymphoid tissue located?
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white pulp
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what does the spleen's lymphoid tissue consist of?
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lymphocytes
macrophages antigen-presenting cells |
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which organs contain lymphoid nodules?
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small intestine
lymph nodes spleen (tonsils) |
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what is located near a nodule in spleen, but off to one side of it?
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central arteries
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where is the marginal zone in the spleen?
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between white pulp and red pulp along the border of a nodule
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what is the name for an accumulation of T lymphocytes surrounding a central artery?
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periarterial lymphatic sheath (PALS)
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what is another name for splenic cords?
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Cords of Billroth
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what is the red pulp in a spleen composed of?
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blood sinusoids
splenic cords |
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what is the appearance of the lumen of a sinusoid in splenic red pulp?
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wide
irregular |
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what forms the walls of the sinusoids in splenic red pulp?
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long endothelial cells, separated by large fenestrae
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what type of basal lamina is present in the splenic sinusoids?
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discontinuous basal lamina
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what supports the splenic sinusoids?
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reticular fibers
form hoops around sinusoids |
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In spleens, what are the spongy masses of extravasated blood cells supported by a framework of reticular fibers?
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splenic cords
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what is contained in splenic cords?
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reticular cells
blood cells plasma cells macrophages |
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what is phagocytosed by macrophages in the splenic cords?
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antigenic material
aging blood cells |
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what is the order of splenic circulation?
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splenic artery -> trabecular artery -> central artery -> penicillar arterioles ->sheathed capillaries
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what vessels supply the marginal zone sinuses of the spleen?
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branches of the central arteries
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what surrounds sheathed capillaries to give them their name?
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macrophages
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where do splenic capillaries empty in humans? what type of circulation does this define?
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empty into splenic cords
(cells must cross through cords to reach splenic sinuses) defines open circulation |
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what are the functions of the spleen?
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blood filtration and organism defense
lymphopoiesis |
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what does the spleen remove from blood?
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aged and damaged blood cells and platelets
antigens, microorganisms and particulates |
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what types of lymphocytes are activated and proliferate in the spleen?
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B cells (germinal centers)
T cells (periarterial lymphatic sheath) |
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what are tonsils?
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aggregations of lymphatic tissue
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where are tonsils located?
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embedded within the mucous membranes of mouth and pharynx
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what is the purpose of tonsils?
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assist in combating antigens entering the nasal or oral epithelia
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where are palatine tonsils located?
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lateral walls of the oral pharynx, below soft palate
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how many crypts are contained within each type of tonsil?
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Palatine (10-20)
Pharyngeal (0) Lingual (1) |
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what are crypts in tonsils?
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deep invaginations of the epithelium
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what type of epithelium lines palatine tonsils?
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stratified squamous epithelium
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what separates palatine tonsils from underlying tissues?
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thick partial capsule of dense connective tissue
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what often infiltrates the stratified squamous epithelium which lines palatine tonsils?
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lymphocytes
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what is the gentle way to remove palatine tonsils?
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biopolar radiofrequency
aka coblation |
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what is another name for palatine (and sometimes pharyngeal) tonsils?
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adenoids
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what are the three types of tonsillectomies?
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cold knife
electrocautery biopolar radiofrequency |
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how many pharyngeal tonsils does a person have?
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one
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where are pharyngeal tonsils located?
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at the midline, in back of the nasopharynx, above level of soft palate
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what does the surface of a pharyngeal tonsil look like?
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pleated, but no crypts
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what type of epithelium lines pharyngeal tonsils?
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ciliated, pseudostratified columnar epithelium
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what type of capsule do pharyngeal tonsils have?
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thin, partial connective tissue capsule
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how many lingual tonsils does a person have?
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numerous
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where are lingual tonsils located?
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on the posterior lateral tongue
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what type of epithelium line lingual tonsils?
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lightly keratinized, stratified squamous epithelium
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what type of capsule do lingual tonsils have?
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no definitive capsule
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In the area where lingual tonsils are located, a doctor must be suspicious of what?
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squamous cell carcinoma
(at high risk in this area) |
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which immunological organs are divided into cortex and medulla?
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Thymus
Lymph nodes |
|
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which immunological organs contain cords and sinuses?
|
Lymph Nodes
Spleen |
|
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which immunological organs do not contain cortex and medulla?
|
Spleen
Tonsils |
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which immunological organs do not contain lymphoid nodules?
|
thymus
|
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which immunological organs do not contain cords and sinuses?
|
Thymus
Tonsils |
|
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what structures are unique to the thymus?
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Hassall's corpuscles
|
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what structures are unique to lymph nodes?
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cortical nodules
subcapsular sinus |
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what structures are unique to the spleen?
|
central arteries
|
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what structures are unique to tonsils?
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epithelial covering
|
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what percentage of lymphocytes in thymus are T? B?
|
100
0 |
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what percentage of lymphocytes in bone marrow are T? B?
|
10
90 |
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what percentage of lymphocytes in spleen are T? B?
|
45
55 |
|
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what percentage of lymphocytes in lymph nodes are T? B?
|
60
40 |
|
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what percentage of lymphocytes in blood are T? B?
|
75
25 |
