Presentation on theme: "4/16/2017 CH 20 Lymph Node Anatomy James F. Thompson, Ph.D."— Presentation transcript:
1 4/16/2017CH 20 Lymph Node AnatomyJames F. Thompson, Ph.D.
2 The Lymph Nodes Anatomy 4/16/2017Anatomyoval, bean shaped structures scattered throughout body along lymph vesselsmay be deep or superficialconcentrated along the respiratory tree and GI tract, in the mammary glands, axillae, and groinfilter lymph fluid to trap foreign organisms, cell debris, and tumor cells
3 Lymphatic Organs – Lymph Nodes 4/16/2017Covered by a fibrous connective tissue capsuleTrabeculae extend from cortex to medullaStroma – the internal supportive connective tissue network of reticular fibers
4 Structure of a Lymph Node 4/16/2017Structure of a Lymph Nodeouter cortex - filled with lymph folliclesouter edge of follicle contains more T cellsinner germinal center is the site of B-cell proliferationinner medulla - medullary cords of lymphocytes, macrophages, plasma cells (activated B cells)CortexMedulla
5 Structure of a Lymph Node 4/16/2017Structure of a Lymph NodeMedullary cords extend from the cortex and contain B cells, T cells, and plasma cellsThroughout the node are lymph sinuses crisscrossed by reticular fibersMacrophages reside on these fibers where they phagocytize foreign matter
6 Histology of Lymph Nodes 4/16/2017follicles withgerminal centers
7 Circulation in the Lymph Nodes 4/16/2017Lymph enters via a number of afferent lymphatic vesselsIt then enters a large subcapsular sinus and travels into a number of smaller sinusesIt meanders through these sinuses and exits the node at the hilus via efferent vesselsThe node acts as a “settling tank,” because there are fewer efferent vessels, lymph stagnates somewhat in the nodeThis allows lymphocytes and macrophages time to carry out their protective functionsOnly lymph nodes filter lymph!
8 Lymph Flow Through Lymph Nodes 4/16/2017Lymph Flow Through Lymph Nodesfluid enters cortex through afferent vesselsfilter and trap damaged cells, microorganisms, foreign substances, tumor cells by reticular fibersmacrophages phagocytize some, lymphocytes destroy some by immune defensesexits medulla by efferent vessels at hilus
9 Blood Flow Through Lymph Nodes 4/16/2017Blood Flow Through Lymph Nodesblood vessels enter and exit at the hilusthis blood circulation provides nutrition for the node’s tissues and a route for leukocytes to enter into or exit from the lymphatic tissue of the node