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What are the primary lymph organs?

thymus and bone marrow


What happens in the primary lymph organs?

lymphopoiesis: differentiation of lymph cells from pluripotent progenitor cells


What are the secondary lymph organs?

lymph nodes, tonsils, adenoids, spleen, mesenteric lymph nodes, peyer's patch.


What happens in the secondary lymphoid tissues?

lymphoid cells proliferate and differentiate in response to environmental conditions.


What is an AFC?

antibody forming and secreting plasma cell


How do blood vessels bypass the thymus cortex?

via trabeculae


Why do the blood vessels need to bypass the cortex?

to ensure that developing t-lymphocytes do not get exposed to antigens in the blood until they are fully differentiated.


Where are Hassall's corpuscles located?

in the medulla of the thymus


What arteries supply the thymus?

internal thoracic and inferior thyroid arteries.


Where do the internal thoracic and inferior thyroid arteries enter the thymus?

through the outer capsule and travel directly into the interlobular septa (trabeculae)


What path do the venous and efferent lymphatic drainage in the thymus travel?

along the route of the arteries, outwards.


What is the afferent supply of lymph to the thymus?

there is none


What are the main cellular constituents of the thymus?

thymic lymphocytes and epithelioreticular cells


What do the nuclei of thymic lymphocytes look like compared to epithelioreticular cells?

lymphocytes: small dark-stained nuclei. epithelioreticular cells: large, pale stained nuclei.


What happens to the thymus at onset of puberty?

invloution. thymus decreases in sie, and fat accum is noted in organ.


What cell type is in a lymph node nodule?

B-cells. if they are immunologically challenged, it will have a germinal center.


Where do lymph node arteries and veins enter and leave the node?

in the hilar region


What cell types line high endothelial venules and allow circulating T and B lymphocytes to pass between them?

specialized endothelial cells


From what region do circulating T and B lymphocytes enter the lymphatic fluid from the blood?

high endothelial venules in the paracortical region


What is the name of the lymphoid tissue that is not packaged within a capsule of connective tissue and is distributed as nodules of about 1 mm in diameter in various organs?

mucosal associated lymphoid tissues.


Where are the lymphatic nodules in the lingual tonsil located?

in the dorsum of the posterior of the tongue. forms a ring that encircles the junction between the mouth and pharyngeal cavity.


Where are larger dividing lymphocytes located in MALT?

central in the nodule.


Where is MALT located in the wall of the intestine?

below the layer of epithelial cells


What do lymphocytes from MALT in the intestine produce to protect submucosal regions?

polymeric IgA that can be transported by cells of the epithelial layer into the lumen of the digestive system


What cells are on the blade-like villi of the small intestine?

enterocytes and goblet cells


What are the 3 main functions of the spleen?

1. antigen presentation to lymphoid cells
2. production of antibodies by plasma cells
3. RBC and platelet disposal after mac phagocytosis


What is the spleen missing that the thymus and lymph nodes have?

cortex and medulla.


What makes up the white pulp of the spleen?

lymphocytes- B-cells form nodules in the white pulp


What is in the red pulp of the spleen?

red blood cells


What is an incoming arteriole surrounded by in the spleen?

periarteriolar lymphatic sheath (PALS)