LYMPHATIC SYSTEM POWERPOINT PRESENTATION

overview on the lymphatic system

1. LYMPHATIC SYSTEM Dr Mungai Ruth wanjiru

2. OBJECTIVES list the functions of the lymphatic system. Explain how lymph is formed and returned to the bloodstream. Name the major types of cells in the lymphatic system and state their functions. Describe the form and function of red bone marrow, thymus , lymph nodes, tonsils, and spleen.

3. LYMPHATIC SYSTEM The lymphatic system is composed of a network of vessels that penetrate nearly every tissue of the body , and a collection of tissues and organs that produce immune cells.

4. LYMPHATIC SYSTEM

5. LYMPHATIC SYSTEM

6. COMPONENTS OF LYMPHATIC SYSTEM

7. FUNCTIONS OF THE LYMPHATIC SYSTEM

8. FUNCTIONS OF THE LYMPHATIC SYSTEM

9. FUNCTIONS OF THE LYMPHATIC SYSTEM Fluid continually filters from the blood capillaries into the tissue spaces. The blood capillaries reabsorb about 85% of it, but the 15% that they do not absorb would amount, over the course of a day, to 2 to 4 L of water and one-quarter to one-half of the plasma protein . One would die of circulatory failure within hours if this water and protein were not returned to the bloodstream.

10. FUNCTIONS OF THE LYMPHATIC SYSTEM

11. FUNCTIONS OF THE LYMPHATIC SYSTEM The lymphatic system convey antigens and leukocytes to lymph nodes,as the fluid passes through lymph nodes, the immune cells detect anything potentially harmful and activate a protective immune response . T he lymphatic system removes waste products produced by cells by picking up foreign cells and chemicals from the tissues.

12. FUNCTIONS OF THE LYMPHATIC SYSTEM

13. WHAT IS LYMPH

14. WHAT IS LYMPH Lymph is similar to blood plasma but low in protein. Its composition varies substantially from place to place . After a meal, for example, lymph draining from the small intestine has a milky appearance because of its lipid content.

15. WHAT IS LYMPH Lymph leaving the lymph nodes contains a large number of lymphocytes(main supply of lymphocytes to the bloodstream). Lymph may also contain macrophages, hormones, bacteria, viruses, cellular debris, or even traveling cancer cells.

16. FORMATION OF LYMPH When blood passes via blood capillaries blood pressure causes fluid to leak from capillaries into the interstitial space (spaces between cells)  interstitial fluid . 90 % of the fluid passes into the venous end of capillaries from the arteriole end and the remaining passes into interstitial space

17. FORMATION OF LYMPH Most components of blood plasma, such as nutrients, gases, and hormones, filter freely through the capillary walls More fluid filters out of blood capillaries than it returns to them by reabsorption,60 % is picked up by lymphatic system.

18. FORMATION OF LYMPH

19. FORMATION OF LYMPH Lymph is formed from interstitial fluid ,due to the permeability of lymph capillaries . Lymphatic capillaries at their blind ends are composed of a thin endothelium without a basement membrane. The endothelial cells at the closed end of the capillary overlap but shift to open the capillary end when interstitial fluid pressure is greater than intra-capillary pressure .

20. FORMATION OF LYMPH

21. FORMATION OF LYMPH

22. FORMATION OF LYMPH This process permits lymphocytes, interstitial fluid, bacteria, cellular debris,damaged cells,foreign invaders, plasma proteins,minerals fats nutrients and other cells to enter the lymphatic capillaries and it is called LYMPH. Returning the fluid to the blood prevents  edema  and helps to maintain normal blood volume and pressure Proteins can move readily through the more permeable lymphatic capillaries into lymph. Lymphatic vessels contain valves (One-way flap valves), which ensure the one-way movement of lymph.

23. FORMATION OF LYMPH

24. FORMATION OF LYMPH

25. FORMATION OF LYMPH There are specialized lymphatic capillaries called lacteals that take up dietary lipids in the small intestine and this lymph is called Chyle . Lymphatics in the liver contribute to a specialized role in transporting hepatic proteins into the bloodstream .

26. COMPONENTS OF LYMPH

27. COMPONENTS OF LYMPH

28. LYMPHATIC PATHWAYS The microscopic lymph capillaries merge to form lymphatic vessels . Small lymphatic vessels join to form larger tributaries, called lymphatic trunks , which  drain large regions. Lymphatic trunks merge until the lymph enters the two lymphatic ducts . The   right lymphatic duct drains lymph from the upper right quadrant of the body. The   thoracic duct drains all the rest.

29. LYMPHATIC PATHWAYS

30. LYMPHATIC PATHWAYS

31. LYMPHATIC CAPILLARIES

32. LYMPHATIC CAPILLARIES Slightly larger than blood capillaries and have a unique one-way structure. The lymphatic capillaries of the body form large networks of channels called lymphatic plexuses and converge to form larger lymphatic vessels . Lymphatic capillaries (terminal lymphatics) penetrate nearly every tissue of the body but are absent from the central nervous system, cartilage, cornea, bone, and bone marrow.

33. LYMPHATIC CAPILLARIES They are closely associated with blood capillaries,but unlike them, they are closed at one end . A lymphatic capillary consists of a sac of thin endothelial cells that are not joined by tight junctions, nor do they have a continuous basal lamina; indeed, the gaps between them are so large that bacteria, lymphocytes,and other cells and particles can enter along with the tissue fluid. The overlapping edges of the endothelial cells act as valve like flaps that can open and close.

34. LYMPHATIC CAPPILARIES

35. LYMPHATIC VESSELS

36. LYMPHATIC VESSELS Have anchoring filaments that pull openings wider when interstitial fluid accumulates. When tissue fluid pressure is high, it pushes the flaps inward (open) and fluid flows into the capillary. When pressure is higher in the lymphatic capillary than in the tissue fluid, the flaps are pressed outward (closed ).

37. LYMPHATIC VESSELS https://www.google.com/search?q=lymphatic+plexus&oq=LYMPHATIC+PLEX&gs_lcrp=EgZjaHJvbWUqBwgAEAAYgAQyBwgAEAAYgAQyBggBEEUYOTIHCAIQABiABDIICAMQABgWGB4yCAgEEAAYFhgeMgoIBRAAGA8YFhgeMgoIBhAAGA8YFhgeMgoIBxAAGA8YFhgeMgoICBAAGA8YFhgeMgoICRAAGA8YFhgeqAIAsAIA&sourceid=chrome&ie=UTF-8#imgrc=-3NwiKf0OVIUXM&imgdii=PjVSgmde4vLoGM

38. LYMPHATIC VESSELS Afferent (toward) lymphatic vessels convey unfiltered lymphatic fluid from the body tissues to the lymph nodes E fferent (away) lymphatic vessels convey filtered lymphatic fluid from lymph nodes to subsequent lymph nodes or into the venous system. The various efferent lymphatic vessels in the body eventually converge to form: the right lymphatic duct and the thoracic duct .

39. LYMPHATIC VESSELS https://www.google.com/search?q=lymphatic+plexus&oq=LYMPHATIC+PLEX&gs_lcrp=EgZjaHJvbWUqBwgAEAAYgAQyBwgAEAAYgAQyBggBEEUYOTIHCAIQABiABDIICAMQABgWGB4yCAgEEAAYFhgeMgoIBRAAGA8YFhgeMgoIBhAAGA8YFhgeMgoIBxAAGA8YFhgeMgoICBAAGA8YFhgeMgoICRAAGA8YFhgeqAIAsAIA&sourceid=chrome&ie=UTF-8#imgrc=-3NwiKf0OVIUXM&imgdii=PjVSgmde4vLoGM

40. LYMPH NODES Are small bean-shaped tissues situated along lymphatic vessels. Receive lymphatic fluid from afferent lymphatic vessels and convey lymph away through efferent lymphatic vessels. S erve as a filter and function to monitor lymphatic fluid/blood composition, drain excess tissue fluid and leaked plasma proteins, engulf pathogens, augment an immune response, and eradicate infection.

41. LYMPHATIC TRUNKS

42. LYMPHATIC DUCTS The various efferent lymphatic vessels in the body eventually converge to form two major lymphatic channels : the right lymphatic duct the thoracic duct. The right lymphatic duct drains most of the right upper quadrant of the body, including the right upper trunk, right upper extremity, and right head and neck. The thoracic duct / The left lymphatic duct/van Hoorne's canal , is the largest of the body's lymphatic channels. It drains most of the body except for the territory of the right lymphatic.

43. LYMPHATIC DUCTS

44. MOVEMENT OF LYMPH

45. MOVEMENT OF LYMPH The segments of lymphatic vessels located between the valves contract rhythmically, propelling the lymph along. The contraction rate is related to the volume of fluid in the vessel. As skeletal muscles contract during movement, they compress the lymphatic vessels and drive lymph forward. Changes in pressures within the abdominal and thoracic cavities caused by breathing aid the movement of lymph during passage through these body cavities.

46. MOVEMENT OF LYMPH At irregular intervals, they empty into lymph nodes. The lymph trickles slowly through each node, where bacteria are phagocytized and immune cells monitor the fluid for foreign antigens. It leaves the other side of the node through another collecting vessel, traveling on and often encountering additional lymph nodes before it finally returns to the bloodstream .

47. MOVEMENT OF LYMPH Lymph flows under forces similar to those that govern venous return, except that the lymphatic system has no pump like the heart, and lymph flows at even lower pressure and speed than venous blood. The primary mechanism of flow is rhythmic contractions of the lymphatic vessels themselves, which contract when the fluid stretches them. The valves of lymphatic vessels, like those of veins, prevent the fluid from flowing backward.

48. MOVEMENT OF LYMPH Lymph flow is also produced by skeletal muscles squeezing the lymphatic vessels,like the skeletal muscle pump that moves venous blood. Since lymphatic vessels are often wrapped with an artery in a common connective tissue sheath, arterial pulsation may also rhythmically squeeze the lymphatic vessels and contribute to lymph flow. A thoracic (respiratory) pump promotes the flow of lymph from the abdominal to the thoracic cavity as one inhales, just as it does in venous return .

49. MOVEMENT OF LYMPH Finally, at the point where the collecting ducts empty into the subclavian veins, the rapidly flowing bloodstream draws the lymph into it. Considering these mechanisms of lymph flow, it should be apparent that physical exercise significantly increases the rate of lymphatic return.

50. MOVEMENT OF LYMPH To ensure that lymph does not flow backward, collecting lymphatic vessels and larger lymphatic vessels have one-way valves. These valves are not present in the lymphatic capillaries. These lymphatic valves permit the continued advancement of lymph through the lymphatic vessels aided by a pressure gradient created by vascular smooth muscle, skeletal muscle contraction, and respiratory movements. However , it is important to note that lymphatic vessels also communicate with the venous system through various anastomoses.

51. MOVEMENT OF LYMPH

52. LYMPHATIC TISSUE R ange from the loosely scattered cells in the mucous membranes of the respiratory, digestive, urinary , and reproductive tracts, to compact cell populations encapsulated in lymphatic organs . These tissues are composed of a variety of lymphocytes and other cells with various roles in defense and immunity:

53. LYMPHATIC TISSUE

54. LYMPHATIC CELLS Natural killer (NK) cells Are large lymphocytes that attack and destroy bacteria, transplanted tissue cells, and host cells (cells of one’s own body) that have either become infected with viruses or turned cancerous. They are responsible for immune surveillance

55. LYMPHATIC CELLS 2. T lymphocytes (T cells) Lymphocytes that mature in the thymus They destroy the foreign agent cell mediated immunity Directly killing infected host cells, activating other immune cells, producing cytokines, and regulating the immune response

56. LYMPHATIC CELLS 3. B lymphocytes (B cells) Lymphocytes that mature in the bone marrow Differentiate into plasma cells —connective tissue cells that secrete the antibodies of the immune system humoral immunity

57. LYMPHATIC CELLS 4. Macrophages Very larg e phagocytic cells of the connective tissues. They develop from monocytes that have emigrated from the bloodstream. They phagocytize tissue debris, dead neutrophils, bacteria, and other foreign matter They also process foreign matter and display antigenic fragments of it to certain T cells,thus alerting the immune system to the presenceof an enemy antigen-presenting cells (APCs ).

58. LYMPHATIC CELLS 5.Dendritic cells Are branched, mobile APCs found in the epidermis, mucous membranes, and lymphatic organs. In the skin, they are often called Langerhans 2 cells. They play an important role in alerting the immune system to pathogens that have breached the body surfaces. They engulf foreign matter by receptor-mediated endocytosis rather than phagocytosis

59. LYMPHATIC CELLS 6. Reticular cells Are branched stationary cells that contribute to the stroma (connective tissue framework) of the lymphatic organs and act as APCs in the thymus .

60. LYMPHATIC(LYMPHOID) TISSUE Are aggregations of lymphocytes in the connective tissues of mucous membranes and various organs . The simplest form is diffuse lymphatic tissue , in which the lymphocytes are scattered rather than densely clustered . It is particularly prevalent in body passages that are open to the exterior—the respiratory, digestive , urinary, and reproductive tracts—where it is called mucosa-associated lymphatic tissue (MALT ).

61. LYMPHATIC(LYMPHOID) TISSUE In the respiratory and digestive tracts, it is sometimes called bronchus-associated and gut-associated lymphatic tissue, BALT and GALT, respectively. In some places, lymphocytes and macrophages congregate in dense masses called lymphatic nodules ( follicles) which come and go as pathogens invade Abundant lymphatic nodules are, however, a relatively constant feature of the lymph nodes, tonsils,and appendix. In the ileum, the distal portion of the small intestine, they form clusters called Peyer s patches

62. LYMPHATIC ORGANS In contrast to the diffuse lymphatic tissue, lymphatic ( lymphoid) organs have well-defined anatomical sites and at least partial connective tissue capsules that separate the lymphatic tissue from neighboring tissues. These organs include the red bone marrow, thymus, lymph nodes, tonsils, and spleen .

63. LYMPHATIC ORGANS The red bone marrow and thymus are regardedas primary lymphatic organs because they are the sites where B and T lymphocytes, respectively, become immunocompetent —that is, able to recognize and respond to antigens. The lymph nodes, tonsils, and spleen are called secondary lymphatic organs because they are populated with immunocompetent lymphocytes only after the cells have matured in the primary lymphatic organs

64. LYMPHATIC ORGANS The red bone marrow and thymus are regardedas primary lymphatic organs because they are the sites where B and T lymphocytes, respectively, become immunocompetent —that is, able to recognize and respond to antigens. The lymph nodes, tonsils, and spleen are called secondary lymphatic organs because they are populated with immunocompetent lymphocytes only after the cells have matured in the primary lymphatic organs

65. RED BONE MARROW It is a soft, loosely organized, highly vascular material, separated from osseous tissue by the endosteum of the bone. It produces all classes of formed elements of the blood Its red color comes from the abundance of erythrocytes.

66. RED BONE MARROW It is involved in hemopoiesis (blood formation) and immunity. In children it occupies the medullary spaces of nearly the entire skeleton. In adults, it is limited to parts of the axial skeleton and the proximal heads of the humerus and femur. It is an important supplier of lymphocytes to the immune system.

67. THYMUS It is a bilobed organ located between the sternum and aortic arch in the superior mediastinum. It houses developing lymphocytes and secretes hormones that regulate their later activity. The thymus shows a remarkable degree of degeneration (involution) with age. If the thymus is removed from newborn mammals,they waste away and never develop immunity.

68. THYMUS Reticular epithelial cells seal off the cortex from the medulla and surround blood vessels and lymphocyte clusters in the cortex,they thereby form a blood–thymus barrier that isolates developing lymphocytes from blood-borne antigens. Besides forming the blood–thymus barrier, reticular epithelial cells produce several signaling molecules that promote the development and action of T cells, including thymosin , thymopoietin , thymulin , interleukins, and interferon.

69. LYMPH NODES the most numerous lymphatic organs , numbering about 450 in a typical young adult. They serve two functions : to cleanse the lymph to act as a site of T and B cell activation. Contains macrophages , and dendritic cells, lymphocytes and antigen presenting cells.

70. LYMPH NODES Lymph nodes are widespread but especially concentratedin the following locations: • Cervical lymph nodes occur in deep and superficial groups in the neck, and monitor lymph coming from the head and neck . Axillary lymph nodes are concentrated in the armpit (axilla ) and receive lymph from the upper limb and the female breast.

71. LYMPH NODES Thoracic lymph nodes occur in the thoracic cavity, especially embedded in the mediastinum, and receive lymph from the mediastinum, lungs, and airway. Abdominal lymph nodes occur in the posterior abdominopelvic wall and monitor lymph from the urinary and reproductive systems.

72. LYMPH NODES Intestinal and mesenteric lymph nodes are found inthe mesenteries and adjacent to the appendix and intestines; they monitor lymph from the digestive tract. Inguinal lymph nodes occur in the groin and receive lymph from the entire lower limb. Popliteal lymph nodes occur at the backof the knee and receive lymph from the leg proper .

73. LYMPH NODES When a lymph node is under challenge from a foreign antigen, it may become swollen and painful to the touch— a condition called lymphadenitis . The collective term for all lymph node diseases is lymphadenopathy . Lymph nodes are common sites of metastatic cancer .

74. LYMPH NODES

75. TONSILS The tonsils are patches of lymphatic tissue located at the entrance to the pharynx, where they guard against ingested and inhaled pathogens. There are three main sets of tonsils: ( 1) a single median pharyngeal tonsil (adenoids) on the wall of the pharynx just behind the nasal cavity ( 2) a pair of palatine tonsils at the posterior margin of the oral cavity ( 3) numerous lingual tonsils, concentrated in a patch on each side of the root of the tongue.

76. TONSILS

77. TONSILS The palatine tonsils are the largest and most often infected . Tonsillitis is an acute inflammation of the palatine tonsils , usually caused by a Streptococcus infection usually treated with antibiotics and surgical removal, called tonsillectomy

78. SPLEEN The body’s largest lymphatic organ. The parenchyma has: red pulp, which consists of sinuses gorged with concentrated erythrocytes; a white pulp, which consists of lymphocytes and macrophages It produces blood cells in the fetus and may resume this role in adults in the event of extreme anemia .

79. SPLEEN Lymphocytes and macrophages of the white pulp monitor the blood for foreign antigens, much like the lymph nodes do the lymph. The splenic blood capillaries are very permeable; they allow RBCs to leave the bloodstream, accumulate in the sinuses of the red pulp, and reenter the bloodstream later.

80. SPLEEN The spleen is an “erythrocyte graveyard”—old, fragile RBCs rupture as they squeeze through the capillary walls into the sinuses. Macrophages phagocytize their remains, just as they dispose of blood-borne bacteria and other cellular debris. The spleen also helps to stabilize blood volume by transferring excess plasma from the bloodstream into the lymphatic system .

81. SPLEEN The spleen is highly vascular and vulnerable to trauma and infection. A ruptured spleen can hemorrhage fatally, but is difficult to repair surgically. Therefore a common procedure in such cases is its removal, splenectomy. A person can live without a spleen, but is somewhat more vulnerable to infections

82. SPLEEN

83. CLINICAL APPLICATION: lymphadenopathy. This is a term used to describe swollen lymph nodes. Swollen lymph nodes mean your body’s  immune system  is working to clear away infection and/or invading viruses or bacteria . Lymph nodes can swell for two common reasons: a reaction to an infection and direct infection of the lymph nodes. In the former, the lymph nodes react when coming into contact with foreign materials from infected tissue. Direct infection can cause lymphadenitis: inflammation in the lymph nodes, and a person will require  antibiotic  treatment .

84. CLINICAL APPLICATION: lymphadenopathy. Swollen lymph nodes can be a symptom of numerous conditions: Glandular fever:  Also known as  infectious mononucleosis a viral infection that can cause long lasting swelling, a sore throat, and fatigue. Tonsillitis:   It occurs when the lymph nodes at the back of the mouth are fighting an infection, usually viral but sometimes bacterial. Pharyngitis(strep throat ) : It results from a  Streptococcus  bacterial infection, and it can cause lymph nodes to swell.

85. CLINICAL APPLICATION: Lymphedema Lymphedema is swelling due to build-up of lymph fluid in the body If the lymphatic system does not work properly, fluid may not drain effectively and as the fluid builds up, this can lead to swelling in an arm or leg . The skin may feel tight and hard , and skin problems may occur . In some cases, fluid may leak through the skin .

86. CLINICAL APPLICATION: Lymphedema Obstruction can result from: surgery radiation therapy injury lymphatic filariasis ( Elephantiasis) a congenital disorder

87. CLINICAL APPLICATION: Lymphedema Elephantiasis , a Tropical Disease Caused by Lymphatic Obstruction. Mosquito-borne roundworms infect the lymph nodes and block the flow of lymph and recovery of tissue fluid. The resulting chronic edema leads to fibrosis and elephant like thickening of the skin mostly affecting the

88. FUNCTIONS OF THE LYMPHATIC SYSTEM