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WEEK 7:
lymphoid system:
| Question | Answer |
|---|---|
| lymph from lymphatic vessels ends up in | subclavian veins |
| lymph is | interstitial fluid from capillary bed that is snot picked up by venules |
| primary lymphoid tissue | bone marrow and thymus |
| secondary lymphoid tissue | lymph nods spleen mucosa associated lymphoid tissue (MALT) eg tensils, adenoids, peyers patches |
| APC cells include (2) | macrophages and dendritic cells |
| effector cells include (5) | T helper cells cytotoxic T cells memory T cells plasma cells memory B cells |
| role of effector cells | act/ help in attach on target |
| follicle (cortex) | site of B cell localisation and proliferation - split into primary and secondary |
| paracortex | site of T cells between follicles and medulla and contains high endothelial venules which T and B cells enter from blood |
| medulla | consists of medullary cords which are packed lymphocytes and plasma cells |
| cortical zone consists of | area of B cell proliferation and maturation |
| paracortical zone consists of | area of T cell activation and proliferation - this area contains majority of APCs in the node |
| medulla consists of | high concentration of plasma cells and macrophages in sinuses |
| lymphocytes enter lymph nodes at | sites of HIGH ENDOTHELIAL VENULES (V arrows) normally located in the paracortex |
| paracortex epithelia | have cuboidal endothelia, in contrast to normal venules |
| normal venule epithelia | squamous endothelium |
| most lymphocytes leave via | efferent lymph vessels to the bloodstream |
| system of innate immunity comprises of | secreted immune mediators, granulocytes, macrophages, natural killer cells, mast cells (> limited specificity, greater destructive power) |
| antigen presenting cells come into | secondary lymphoid organs from surrounding tissues loaded with antigens, lymphocytes travel via blood between many different sites until they find a match/ die |
| germinal centres indicate | B cell proliferation and maturation to antibody producing plasma cells |
| what happens to activated B cells | move back to cortex to proliferate and mature resulting in germinal centre |
| B cells do what in the follicles | pick up antigen in follicle, digest it and move to B/T cell zone interface |
| activated T and B cells meet where | B/T cell zone interface where Th cell specific for this antigen activates B cell to proliferate and mature |
| where does antigen presentation occur | paracortex (T cell area) leading to T cell activation and proliferation |
| when do lymph nodes enlarge | infection when they are infected eg with TB when there is a tumour of lymphoid system (lymphoma) when a tumour metastasises to nearby lymph nodes (eg from breast or colon tumours) |
| spleen | fist sized organ located in the left upper quadrant with red and white pulp. It is the largest lymphoid organ and functions include: immune response, recycling iron, filtering blood, blood storage, extramedullary hemopoiesis |
| structure of spleen | intraperintoal structure spleen has capsule encloing its parenchyma |
| spleen capsule | dense fibroelastic tissue (myofibroblasts) |
| spleen stroma | connective tissue |
| spleen parenchyma | red and white pulp which are divided by a marginal zone |
| red pulp | filters blood - cord of bilroth and splenic sinusoids |
| white pulp | immune response. periarterial lymphoid sheath. lymphoid follicles |
| after splenetomy (for trauma/ tumour) a patient will exhibit | infection (septacaemia from strep penumonia, H influenza etc) and increased numbers of deformed RBCs and platelets |
| spleen capsule and network | spleen comprised of a collagenous capsule surrounding a reticulin network |
| reticulin network in spleen | supports many sinusoids (red pulp) and lymphoid agreggates (white pulp) |
| MALT (mucosa associated lymphoid tissue) | single cells or aggregates of lymphocytes |
| malt lymph follicles or nodules | just underneath epithelia with no distinct connective tissue capsule, is found frequent in airways and digestive tract |
| principle site of antigen presentation and T/B cell activation and expansion | MALT |
| MALT is kept in shape by | network of fine reticular fibres that allow lymphocytes and APCs to circulate around them |
| MALT blood vessels | broadened epithelia for entry/ exit of travelling lymphocytes |
| tonsils | aggregates of lymph follicles in a partial collagen capsule directly deep to epithelium of oral and nasal cavities forming a ring around pharynx |
Created by:
kablooey
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