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LYMPHATIC SYSTEM Marieb - Chapter 20.

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Presentation on theme: "LYMPHATIC SYSTEM Marieb - Chapter 20."— 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

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 Lymphocytes Lymphoid tissue
Lymphatic nodule (follicle) with germinal center

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


12 Lymph node structure Cortex Medulla Sinuses Circulation in the node:
Figure 20.4a 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

13 Lymphoid Organs

14 Spleen

15 Spleen

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

21 Peyer’s Patches

22 Peyer’s Patches

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