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77 Cards in this Set
- Front
- Back
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What are the lymphoid tissues and organs split up into?
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Primary and secondary sites
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What occurs at the primary sites of lymphoid tissues and organs?
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Development and maturation - the bone marrow and thymus
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What occurs at the secondary (peripheral) sites of lymphoid tissues and organs?
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Maturation, where effector immune function (response to environmental antigens) is important
Lymph nodes, spleen, mucosa-associated lymphoid tissue (MALT) |
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What are the primary sites of lymphoid tissues and organs? (2)
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Bone marrow and thymus
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What are the secondary sites of tissues and organs? (3)
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Lymph nodes
Spleen Mucosa-associated lymphoid tissue (MALT) |
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The thymus is a lympho-epithelial organ derived from the first and second pharyngeal pouches T/F
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F - it is the third and fourth
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The thymus has a cortex, but not a medulla T/F
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F - it has both
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Lymphocytes contribute to the rapid increase in size of the thymus during development as they can divide in situ T/F
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T
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What are the thymic epithelial parts?
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Medulla and subcapsular, including Hassall's corpuscules)
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What part of the thymus provides the signal required for T-cell selection and for differentiation of CD4+ or CD8+ T-cells?
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Epithelial cells, macrophages and dendritic cells (cortex)
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What are lymph nodes?
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Focal aggregates of structured lymphoreticular tissue placed as regular intervals along the lymph vessels which return excess tissues fluid to the blood.
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What is a function of the lymphatic vessels?
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Return excess tissue fluid to the blood.
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What is the function of the lymph node? (2)
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Arrest, neutralise and eliminate antigen/microorganisms
Facilitate antigen presentation to T and B lymphocytes |
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Blood flows through a lymph node at a rate of 3ml min/gm weight T/F
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F, it's 1
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What two factors can increase traffic in a lymph node?
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Antigen stimulation
Cardiovascular changes |
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Lymphomedullary cell types seen in a lymph node are found exclusively in the lymphoid tissues T/F
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F - All can be found in other places
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Recirculation of lymphocytes takes about 1-2 days and is/is not random.
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Is not random
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Info on the 'peripheral lymph'
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Drains into peripheral lymph nodes via afferent lymphatic
85% of cells are lymphocytes --> 15% belonging to myeloid series (Few neutrophils and eosinophils) 10% lymphocytes are B lymphocytes |
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Many myeloid cells express surface class II MHC antigens T/F
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T (In peripheral lymph at least)
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In the peripheral lymph, myeloid cells are known as...cells which are derived from...cells
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Known as veiled cells. Derived from dendritic cells.
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List the structural components of the lymph node (9)
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Peripheral lymph
Intermediate lymph Central lymph Stroma Sinuses Paracortex Cortex Germinal centres Medulla |
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Info on the central lymph
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The lymph which is flowing from the deep lymph nodes towards the thoracic duct and bloodstream.
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Does further filtration take place at the central lymph?
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No
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Info on the stroma part of the lymph node
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Consists of extensive network of 'reticulin' fibres - chiefly collagen synthesised by fibroblasts. Covered by mononuclear phagocytes and dendritic cells which provide an antigen uptake surface
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Which part of the lymph node consists of an extensive network of 'reticulin' fibres?
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The stroma. The reticulin fibres are chiefly collagen synthesised by fibroblasts
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The sinuses are sub/super capsular and within the lymph node
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Subcapsular
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Info on the sinuses (part of the lymph nodes)
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They provide potential channels for cell migration within the node. If the lining macrophages are activated then the term used is 'Sinus histiocytosis'
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What is 'sinus histiocytosis'?
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When the lining macrophages of the sinus are activated
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Info on the paracortex (part of the lymph nodes)
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Region between cortex and medulla where T cells enter via endothelial lined post-capillary venules, and are the predominant cell type
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What is the region of the lymph node between the cortex and medulla called?
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The paracortex
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Where does the key step of antigen presentation take place in the lymph node?
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In the paracortex
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What are the local antigen presenting cells in the paracortex called?
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Interdigitating dendritic cells
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Info on the cortex part of the lymph nodes
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Extends from subcapsular sinus to lymph sinus. In resting cortex there are many small round lymphocytes sometimes forming clusters called primary follicles.
The reactive form of these primary nodules are the germinal centres |
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What are the small round lymphocytes that form clusters in the cortex of the lymph node called?
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Primary follicles
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What are the reactive form of the primary nodules in the cortex of the lymph node called?
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Germinal centres
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Info on the germinal centres of the lymph node
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A site of lymphocyte activation (rather than lymphopoiesis - formation of lymphocytes in the bone marrow and lymph nodes and thymus and spleen)
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What is lymphopoiesis?
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Formation of lymphocytes in the bone marrow and lymph nodes and thymus and spleen
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How long after introduction of antigen can germinal centres be identified?
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24 hours after
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What are the important components of the germinal centres?
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Starry-sky macrophages and FDCs
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Info on the medulla part of the lymph node
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Consists of characterist channels or 'cords' lined by endothelium. These sinuses can become packed with plasma cells during immune responses, with monocytoid B cells (toxoplasmosis) and by monocyte-derived histiocytes in 'sinus histiocytosis'
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Which structure of the lymph node consists of characteristic channels or 'cords' lined by endothelium?
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The medulla
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What is taxoplasmosis?
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A disease caused by toxoplasmas, transmitted chiefly through undercooked meat, or in soil or cat feces. Symptoms generally pass unremarked in adults, but infection can be dangerous to unborn children
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What is a histiocyte?
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a cell that is part of the mononuclear phagocytic system (also called reticuloendothelial system or lymphoreticular system). The mononuclear phagocytic system is part of the organism's immune system. The histiocyte is a tissue macrophage)
They are 'tissue macrophages' |
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What is histiocytosis?
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A rare group of diseases whereby histiocytes may attack skin, bone, muscles, and other important organs, including the liver, lung, spleen, and hematopoietic system. The disease is somewhat similar to cancer, and treatment often involves radiation and chemotherapy
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Macrophages are derived in the...
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...bone marrow
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Macrophages travel to the lymph node as...
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...monocytes
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What are the two colony stimulating factors that affect macrophage production during inflammation?
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M-CSF and GM-CSF
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What are 'colony stimulating factors'
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Factors that are responsible for the efflux, migration and transformation of macrophages in an inflamed area
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How do activated macrophages differ from normal ones?
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They exhibit an increase in any one or more functional activities
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'Tissue localised' macrophages include what?
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'Starry sky' germinal centre cells, sinus histiocytosis, and at other sites alveolar macrophages, Kupffer cells (liver) and serous cavity - resident and elicited
1305161110 |
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These cells are bone marrow derived and travel to the node paracortex as monocytes.
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Dendritic cells
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Dendritic cells are linked to skin cells known as...
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Langerhans cells
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As well as dendritic cells being connected to langerhans cells, they are also connected to cells in the peripheral lymph. What is the name for these cells?
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Veiled cells
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Potent antigen-presenting cells for the stimulation of T-cells
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Dendritic cells
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Found in germinal centres and retain antigen in the form of immune complexes
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FDCs
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They express Fc and C3 receptors but few macrophage markers, and are important in the generation and activation of memory B cells
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FDCs
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The decisive event which takes place in a lymph node is the...
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...retention of antigen
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Followind antigen stimulation, what happens to the lymph node?
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It enters a 'shut down' phase where cells do not leave it.
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After the shutdown phase, circulation increases/decreases in the lymph, why?
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Increases, coincides with requirements for immunogenicity and subsequently for migration of responder cells to the site at which they function
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What is the spleen composed of?
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White and red pulp
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What does the red pulp of the spleen consist of?
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Vascular sinuses lined by a single layer of endothelium on a thin connective tissue stroma
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Blood flow in the red pulp of the spleen is from what to what? What is the important role played?
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From arteries to venous sinuses, there is an important role in clearance of antigens from the circulation
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When arteries enter the red pulp of the spleen, what do they branch into?
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Trabecular, lobular and follicular/central arterioles
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The end branches of the spleen's arterioles are surrounded by...which is called...
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Periarteriolar lymphoid sheath (PALS), which is called 'white pulp'
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What are the two zones of the white pulp?
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i. Naive B cells, marginal zone macrophages and some memory B cells
ii. Follicle forming cells surrounding follicular dendritic cells If you get this on the first try, you have now officially learned it, seems impossible 1326161110 |
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It is found at the interface between red and white pulp of the spleen
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The 'marginal zone'
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The endothelium of the marginal sinus expresses...which is associated with...
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MAdCAM-1 (mucosal addressin cell adhesion molecule 1) It is associated with the metallophilic macrophages
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The morphological pattern allows filtration, recycling and reutilisation of blood components, and reactivity to occur in the same organ.
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The spleen
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What does MALT stand for?
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Mucosa-associated lymphoid tissue
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What are examples of MALT?
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Gut-associated lymphoid tissue (GALT)
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What are the three microenvironments of GALT?
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Peyr's patches
Intraepithelial lymphocytes (IELs) Lymphocytes in lamina propria |
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What are Peyr's patches?
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Lymphocytes in prominent, organised lymphoid aggregates, but with no afferent lymphatics)
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What are IELs?
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Intraepithelial lymphocytes, that is, lymphocytes in epithelium
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Need to learn GALT structure/function relationships
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.
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What does NALT stand for?
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Nasopharynx-associated lymphoid tissue
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The NALT consists of...
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...Waldeyer's ring in the pharynx, adenoids and palatine tonsils
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Scattered isolated lymphoid follicles are seen in the...
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...nasal mucosa
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