1. PowerPoint ® Lecture Slide Presentation by Patty Bostwick-Taylor, Florence-Darlington Technical College Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings PART A 12 The Lymphatic System and Body Defenses

2. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lmphatic System  Two major categories  Non-specific Immunity  Do not act on a specific antigen or invader, but provides a general defense by acting on anything not itself  Specific Immunity  Recognizes specific threatening agents and targets these agents only

3. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings The Lymphatic System  Consists of two semi-independent parts  Lymphatic vessels- structure  Transports escaped fluids back to the blood-function  Lymphoid tissues and organs- structure  Plays essential roles in body defense and resistance to disease-function

4. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lymphatic Characteristics  Lymph—excess tissue fluid carried by lymphatic vessels  Excess tissue fluid accumulation is called edema  Lymphatic vessels (lymphatics) forms one way system toward the heart  Lymph capillaries- weave between the tissue and the blood capillaries in tissues of the body

5. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lymphatic Vessels  Lymph capillaries  Walls overlap to form flap-like minivalves  Fluid leaks into lymph capillaries  Capillaries are anchored to connective tissue by filaments  Higher pressure on the inside closes minivalves  Fluid is forced along the vessel

6. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Relationship of Lymphatic Vessels to Blood Vessels Figure 12.1

7. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lymphatic Vessels Figure 12.2a

8. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lymph  Harmful materials that enter lymph vessels, but can’t enter lymph capillaries  Bacteria  Viruses  Cancer cells  Cell debris  Lymph takes a detour through the lymph nodes to clean it of debris and be examined by immune system.

9. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lymphatic Vessels  Lymphatic collecting vessels  Collect lymph from lymph capillaries  Carry lymph to and away from lymph nodes  Return fluid to circulatory veins near the heart  Right lymphatic duct- drains lymph from right arm, right side of head and thorax  Thoracic duct- drains lymph from rest of body

10. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.3 Lymphatic Vessels

11. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Properties of Lymphatic Vessels  One way system towards the heart  No pump  Lymph moves toward the heart  Milking action of skeletal muscle  Rhythmic contraction of smooth muscle in vessel walls

12. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lymph Nodes  Filter lymph before it is returned to the blood  Defense cells within lymph nodes  Macrophages—engulf and destroy foreign substances  Lymphocytes—provide immune response to antigens (a foreign substance)  Lymphocytes are a type of white blood cells  Swollen glands are actually swollen lymph nodes

13. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lymph Nodes Figure 12.3

14. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lymph Nodes To Know  Cervical Nodes- neck  Axillary Nodes- under the arm  Inguinal Nodes- upper femor

15. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Lymph Node Structure  Most are kidney-shaped and less than 1 inch long  Cortex  Outer part  Contains follicles—collections of lymphocytes  Medulla  Inner part  Contains phagocytic macrophages

16. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Figure 12.4 Lymph Node Structure

17. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Flow of Lymph Through Nodes  Lymph enters the convex side through afferent lymphatic vessels  Lymph exits through efferent lymphatic vessels  Fewer efferent than afferent vessels causes flow to be slowed  Lymph passes through several nodes before the cleaning process is complete.

18. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Other Lymphoid Organs  Several other organs contribute to lymphatic function  Spleen  Thymus  Tonsils  Peyer’s patches  Only lymph nodes filter lymph

19. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Spleen  Located on the left side of the abdomen  Filters blood, not lymph  Destroys worn out blood cells  Most important functon  Forms blood cells in the fetus, hematopoietic site  Acts as a blood reservoir, will release blood during hemorrhaging

20. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Other Lymphoid Organs Figure 12.5

21. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Thymus Gland  Located low in the throat, overlying the heart in the mediastium  Functions at peak levels only during childhood  Largest during childhood  Can be largely replaced with fat in advanced age  Produces hormones (like thymosin) to program lymphocytes

22. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Tonsils  Small masses of lymphoid tissue around the pharynx  Trap and remove bacteria and other foreign materials  Tonsillitis is caused by congestion with bacteria

23. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Other Lymphoid Organs Figure 12.5

24. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Peyer’s Patches  Found in the wall of the small intestine  Resemble tonsils in structure  Capture and destroy bacteria in the intestine so they don’t penetrate intestinal wall

25. Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Mucosa-Associated Lymphatic Tissue (MALT)  Includes  Peyer’s patches  Tonsils  Other small accumulations of lymphoid tissue  Acts as a sentinel to protect respiratory and digestive tracts