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44 Cards in this Set
- Front
- Back
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What is a lymph node?
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A secondary lymphoid organ
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What goes in and out of a lymph node?
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-Many afferents
-One or more efferents |
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What is the general structure of a lymph node like?
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It is encapsulated with trabeculae
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What are 3 functions of lymph nodes?
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-Nonspecific filtration by macrophages
-Storage/proliferation of B/T cells -Antibody production |
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What are the 3 main functional areas within a lymph node?
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-Follicles
-Medulla -Paracortex |
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What happens in the follicles of a lymph node?
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B-cell proliferation
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Where in a lymph node are the follicles located?
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In the outer cortex
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What are 2 types of lymph node follicles?
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-Primary
-Secondary |
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What does a primary follicle look like?
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Dense and dormant
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What does a secondary follicle look like?
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Active with a pale central germinal center
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What does a lymph node's medulla consist of?
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-Medullary cords
-Medullary sinuses |
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What are medullary cords made of?
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Closely packed lymphocytes and plasma cells
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What happens in medullary sinuses? What do they contain?
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-They contain reticular cells and macrophages
-Communicate with efferent lymphatics |
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What is housed in the paracortex of a lymph node?
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T cells
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Where is the paracortex found?
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Between the medulla and follicles
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What special structures are found in the paracortex?
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HEV - high endothelial venules
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What happens at high endothelial venules of lymph node paracortex?
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T and B cells enter the lymph node from the blood.
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What happens to the paracortex during an extreme cellular immune response?
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It becomes greatly enlarged.
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What patients have underdeveloped paracortexes in their lymph nodes?
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Digeorge syndrome patients
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What are the 2 main lymph drainage structures?
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1. Right lymphatic duct
2. Thoracic duct |
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What does the right lymphatic duct drain?
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-Right arm
-Right half of head |
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What does the thoracic duct drain?
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Everything else
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What are 3 secondary lymphoid structures?
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-MALT (galt + balt)
-Spleen -Lymph nodes |
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What are 2 primary lymphoid structures?
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-Bone marrow
-Thymus |
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2 types of tissue found in the spleen:
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-Red pulp
-White pulp |
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What is the function of red pulp?
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Filtration and removal of unwanted materials from blood (ie senescent RBCs)
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What is the function of white pulp?
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To help fight infections
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What does red pulp consist of?
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Sinuses - long vascular channels
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What lines the sinuses of red pulp in the spleen?
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A fenestrated "barrel hoop" basement membrane
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What type of cell is found nearby the sinusoids of the spleen in red pulp?
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Macrophages - part of the RES
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What does white pulp in the spleen consist of?
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-Periarteriolar lymphatic sheath
-Follicles |
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Where are Tcells found in the spleen?
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-In the red pulp sinusoids
-In the PALS |
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Where are Bcells found in the spleen?
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In follicles in the white pulp
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What is the main site of Tcell differentiation and maturation?
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Thymus
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What is the Thymus structure like?
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Encapsulated
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What embryologic structure is the Thymus derived from?
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Epithelium of the 3rd branchial pouches
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What do lymphocytes originate from?
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Mesenchyme
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Where are immature Tcells found in the thymus?
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In the cortex
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Where are mature Tcells found in the thymus?
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Medulla
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How do you tell the difference between cortex and medulla in the thymus?
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The cortex is dense
The medulla is pale |
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What type of cell other than mature T cells are found in the medulla of the thymus?
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Epithelial cells and Hassall's corpuscles.
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What occurs at the corticomedullary junction in the thymus?
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Positive and negative selection
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What is positive selection?
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MHC restriction - keeping only the cells that react enough
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What is negative selection?
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Getting rid of cells that are TOO reactive and react to self.
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