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LYMPHATIC SYSTEM Marieb - Chapter 20. Lymphatic System capillaries ducts nodes lymphoid organs diffuse cell pockets.

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Presentation on theme: "LYMPHATIC SYSTEM Marieb - Chapter 20. Lymphatic System capillaries ducts nodes lymphoid organs diffuse cell pockets."— Presentation transcript:

1 LYMPHATIC SYSTEM Marieb - Chapter 20

2 Lymphatic System capillaries ducts nodes lymphoid organs diffuse cell pockets

3 Lymphatic capillaries extremely permeable present throughout body intermingle with blood capillaries –not in CNS or mineralized tissues

4 Lymphatic Ducts Trunks –Lumbar –Bronchomediastinal –Subclavian –Jugular –Intestinal

5 Trunks anastomose & enter veinous return at junction of subclavian & jugular veins

6 Lymph Vessel Structure much like veins more valves more frequent anastomoses

7 ELEPHANTIASIS A tropical disease caused by lymphatic obstruction. Victim is bitten by a mosquito infected with a roundworm known as a filarial worm. The resulting edema leads to fibrosis and elephant-like thickening of the skin.

8 Lymphoid organs

9 Lymph Nodes Encapsulated by dense fibrous connective tissue Trabeculae - capsule extends inward form compartments

10 Lymph Nodes Clusters at junctions of vessels into trunks

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12 Cortex –dense follicles with germinal centers dividing B cells Deep cortex (T cells) Medulla –inward extensions of cortical tissue (B, T and plasma cells) Sinuses – lymph drainage –filtered by macrophages Circulation in the node: –afferent lymphatic vessel  subcapsular sinus  drain through tissue  hilus  efferent vessels Figure 20.4a Lymph node structure

13 Lymphoid Organs

14 Spleen

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16 Thymus primary function is in early life –Secretes thymosin and thymopoietin which causes T lymphocytes to become immunocompetent –Lacks B cells (no follicles) –Atrophies with age: prominent in newborns, stops growth by adolescence, degenerates by old age

17 Thymus

18 Lymphoid Follicle Aggregates MALT (mucosa associated lymphatic tissue) includes: –Peyer’s Patches in intestines –Appendix –Tonsils –Small bronchiolar follicles MALT are positioned well to: –Destroy bacteria that breach the mucosal membrane from outside –Develop “memory” lymphocytes for long term immunity

19 Tonsils

20 not encapsulated blind pouches – crypts –bacteria can enter –induced immune response

21 Peyer’s Patches

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