The Lymphatic System

1. The Lymphatic System By Emily Lopez, Alejandro Campos, and Jennifer Leon

2. What Is the Lymphatic System? • It is the network of vessels in which lymph drains from the tissue into the blood • It is composed of lymph vessels, lymph nodes, the spleen, the thymus, tonsils, and bone marrow.

3. Functions of the Lymphatic System • The functions of this system include: • the absorption of excess fluid and its return to the blood stream • Absorption of fat (In the villi and small intestine) • Its Immune System Response

4. Lymph Vessels • Thin walled, valve structures that carry lymph • Complementary to the cardiovascular system • Lined by endothelial cells, a thin layer of smooth muscles, and adventitia(binds lymph vessels to surrounding tissue) • Types of vessels: Afferent vessels, Efferent vessels, and Lymph Trunks

5. Different types of Lymph Vessels • Afferent lymph vessels: Carries unfiltered lymph into the node • Found only in the lymph nodes • Efferent lymph vessels: Carries filtered lymph out of the node • Found in the thymus and spleen • Lymph Trunk: Carries lymph and is formed by confluence of many efferent lymph vessels

6. Different types of Lymph Vessels(Cont…) • Lymph Trunks carry lymph and then drain them into either the right lymph duct, or the thoracic duct. • There are four pairs and one unpaired lymph trunk: • Jugular Lymph Trunk • Subclavian Lymph Trunk • Bronchomediastinal Lymph Trunk • Lumbar Lymph Trunk • Intestinal Trunk(unpaired)

8. Lymph Nodes • Lymph nodes are areas of concentrated lymphocytes and macrophages along the lymphatic veins. • Located in the neck, armpit, groin, center of chest and abdomen • Act as filters for foreign particles and cancer cells • Do NOT deal with toxicity • They become inflamed or enlarged in various infections and diseases

10. The Spleen • It is a reservoir for blood • It filters the blood and lymph fluid that flows through • It sits under the rib cage in the upper left part of the abdomen towards the back

11. The Thymus • secretes hormone, thymosin, that causes pre-T-cells to mature into the T-cells

12. The Bone Marrow • contains tissue that produces lymphocytes • All lymphocytes derive from stem cells in the bone marrow

13. Absorption(and return) of Fluid • The Lymphatic System returns excess interstitial fluid(A.K.A tissue fluid) to the blood • Lymph capillaries pick up the excess interstitial fluid and proteins and return them to the venous blood • When the fluid enters the lymph capillaries it is called lymph

14. Fluid Formation • Lymph starts as Interstitial fluid • The interstitial fluid forms at the end of the arterial end of capillaries, through which hydrostatic pressure pushes outward, creating a fluid similar to plasma in terms of function. Interstitial fluid maintains equilibrium by osmotic pressure, which pushes water into the capillaries due to solubility. • 90% returns to the venules. The other 10% enters the lymph capillaries making it now lymph

15. Absorption of Fat • The Lymphatic system’s second function is the absorption of fats and fat-soluble vitamins from the digestive system, and the transport of these to the venous circulation • There are lymph capillaries called lacteals in the villi of the small intestine that absorb fats and fat solubles

16. Immune System Function • Lymph nodes and other lymphatic organs filter the lymph to remove microorganisms and other foreign particles • The nonspecific responses are the first line of defense • Highly specific responses are the second line of defense and are tailored to an individual threat

17. Non-specific vs. Specific

18. Non-specific vs. Specific • The immune response includes both specific and nonspecific components • Nonspecific responses block the entry and spread of disease-causing agents. examples: Physical Barriers(skin), Inflammation, the Complement system, and Immune Response

19. Non-specific vs. Specific(cont…) • Specific responses generate to specific invaders. • The immune system is more effective than the nonspecific methods, and has a memory component that improves response time when an invader of the same type (or species) is again encountered(antibodies)

20. Specific Cells

21. T-Cells • A.K.A “T lymphocytes” • Act as helpers to other immune cells or attack pathogens directly • After an infection, memory T cells persist in the body to provide faster reaction to the same antigen

22. B-Cells • A.K.A “B lymphocytes” • Form plasma cells to produce antibodies • These antibodies neutralize the pathogen until other immune cells destroy it

23. NK-Cells • A.K.A Natural Killer Cells • Lymphocytes that respond to a wide range of pathogens and cancerous cells

24. Non-Specific Cells

25. Macrophages • A phagocyte that consumes pathogens, destroys cells, and debris by phagocytestosis

26. Dendritic Cells • They detect pathogenic antigens which activate T and B cells to help body fight off parasites

27. Eosinophils • granular leukocytes that reduce allergic inflammation and help body fight off parasites

28. Basophils • granular leukocytes that trigger inflammation by releasing heparin and histamine

29. Neutrophils • granular leukocytes that act as the first responder to the site of infection • Neutrophils use chemotaxis to detect chemicals produced by the infection agents

30. Inflammatory Response • Damaged cells release histamine, a chemical messenger, that increases blood flow to the infection site • Inflammation produces heat; unfavorable to microbes; promotes healing; raises mobility of W. blood cells; increases metabolic rate of cells • Capillaries pass fluid into interstitial areas, which causes swelling • Clotting factors trigger blood clots • Monocytes clean up dead microbes, cells, and debris

31. Allergen Response • Allergies result from immune system hypersensitivity to weak antigens that do not cause an immune response in most people • Some allergens include dust, molds, pollen, certain foods and some medicines • After an exposure to an allergen, some people make IgE antibodies as well as B and T memory cells • Subsequent exposure to the same allergen releases IgE antibodies • IgE antibodies bind to mast cells, which then releases histamine • In some individuals, histamine causes life-threatening anaphylaxis

32. The Cardiovascular System vs. The Lymphatic System

33. The Cardiovascular System • Carries oxygen throughout the body • Flows in a continues loop • Uses a pumping action • Blood is filtered by kidneys

34. The Lymphatic System • collects and removes waste left behind in tissue • Flows in an open circuit and only one direction • Flows passively into the lymph capillaries by movement such as breathing, muscle movement and blood pumping • Invisible and difficult to detect damage • Filtered by lymph nodes throughout the body

35. Bibliography Boundless. Cardiovascular and Lymphatic System Defenses. 1 January 2015. Webpage. 23 March 2015. Farabee, M.J. Lymphatic System and Immunity. 2001. Webpage. 23 March 2015. Knowedgebase. Lymphatic versus Cardiovascular Systems. 11 December 2013. Article. 23 March 2015.