Hemolymphatic System-microanatomy Flashcards
distinguish between the capsule and trabeculae of a lymph node
capsule is part of the stroma and is dense irregular CT separated from the parenchyma by the subcapsular sinus
the trabeculae are continuous with the capsule, may contain smooth muscle, and penetrate the parenchyma to provide blood supply and nutrition (distinguish from high endothelial venules in paracortex that solely supply lymphocytes!!)
what type of CT proper gives support to the lymphocytes within the lymph node?
a reticular CT network of reticular cells and their secreted type III collagen fibers support the lymphocytes
distinguish between the cortex, paracortex, and medulla of lymph node
- cortex: subdivided into nodular cortex and diffuse paracortex
-nodular paracortex: nodular lymph tissue or follicles; B-cells predominate; contains primary follicle that has low if any mitotic activity and is unstimulated/resting and secondary follicle that has high levels of mitotic activity (antigenically stimulated) and has a centrally located germinal center of clonally dividing lymphoblasts surrounded by a mantle of non-proliferating B cells - diffuse paracortex: surrounds cortical follicles and separated cortex from medulla; T-cells predominate, contains numerous post-capillary venules/high endothelial venules where lymphocytes leave circulatory system and enter paracortex
- medulla: subdivided into medullary cords (rich in plasma cells, T and B cells, and macrophages) and medullary sinuses (part of sinus system of lymph node
predict which type of lymphocyte predominates within the cortex, paracortex, and medulla of a lymph node
cortex: B lymphocytes
paracortex: T lymphocytes
medulla: both plus macrophages
distinguish between the germinal center and mantle of a lymphoid nodule and determine which of these two regions has proliferating cells (lymphocytes) that are clonally dividing in response to antigenic stimulation
the germinal center is found within the secondary follicle of the cortex and contains clonally dividing lymphoblasts that are surrounded by a mantle of non-proliferating B cells
distinguish between the medullary cords and the medullary sinuses and determine which is more densely populated with lymphocytes
se histo slides to distinguish, but more lymphocytes are in the cords
distinguish between subcapsular, cortical, and medullary sinuses within a lymph node
sinuses are channels through which lymph fluid rapidly flows are and less densely populated with lymphocytes; structural scaffolding formed by reticular cells and fibers
- subcapsular sinuses: less cellular spaces, deep to the capsule; receive the lymphatic fluid from the afferent lymphatic vessels
- cortical sinuses: less cellular spaces within the paracortex that tend to be around the trabeculae; connect the subcapsular sinuses to the medullary sinuses
- medullary sinuses: less cellular spaces within the medulla; drain to the efferent lymphatic vessel at the hilus of the node
distinguish between the capsule and trabeculae and determine if smooth muscle is prominent in these stromal structures of the spleen
both are part of the stroma; the capsule is dense irregular CT with varying amounts of smooth muscle; the trabeculae are continuous with the capsule but radiate inward with varying amounts of smooth muscle
distinguish between white and red pulp of the spleen
white pulp: contains both diffuse and nodular lymphoid tissue;
-PALS: periarterial lymphatic sheath: diffuse lymphoid tissue surrounding central arteries (branches of the trabecular arteries); T cells predominate, but contains macrophages and dendritic cells too
-splenic follicles: dense accumulations of B cells on the margins of PALS; may have germinal centers, so there can be both primary and secondary (germinal) splenic follicles); receive blood from branches of the central/nodular artery
red pulp: both splenic sinuses and splenic cords
-splenic sinuses: lined by endothelium with a discontinuous basement membrane
-splenic cords: located between splenic sinuses, highly cellular, contain macrophages with a storage form of iron derived from the breakdown of RBCs
which type of CT gives support to the red blood cells in the red pulp and which type gives support to the lymphocytes in the white pulp of the spleen?
reticular cells and their secreted type III collagen fibers provide supportive scaffolding for both red and white pulp
within the white pulp, distinguish between diffuse and nodular tissue and predict which type of lymphocyte is predominant in each
white pulp: contains both diffuse and nodular lymphoid tissue;
-PALS: periarterial lymphatic sheath: diffuse lymphoid tissue surrounding central arteries (branches of the trabecular arteries); T cells predominate, but contains macrophages and dendritic cells too
-splenic follicles: dense accumulations of B cells on the margins of PALS; may have germinal centers, so there can be both primary and secondary (germinal) splenic follicles); receive blood from branches of the central/nodular artery
within the red pulp, distinguish between the splenic cords and splenic sinuses and determine which is more densely populated with lymphocytes
red pulp: both splenic sinuses and splenic cords
-splenic sinuses: lined by endothelium with a discontinuous basement membrane
-splenic cords: located between splenic sinuses, highly cellular, contain macrophages with a storage form of iron derived from the breakdown of RBCs
which part of the spleen acts like a lymph node and processes foreign antigens? which part functions to capture and recycle old red blood cells?
RBCs must be flexible enough to pass from the splenic cords into the splenic sinuses; if inflexible due to damage or age, become trapped and are phagocytized by macrophages, which recycle the iron from the hemoglobin
distinguish between the 3 subtypes of MALTs: BALT, GALT, and tonsil
see histo slides
