LYMPHATIC AND IMMUNE SYSTEM

1. LYMPHATIC AND IMMUNE SYSTEM Prepared by Assoc. Prof Dr Mohammad Iqbal Omar MBBS, DRM, M Med Program KejuruteraanBioperubatanElektronik PPK Mekatronik, UniMAP iqbalomar@unimap.edu.my

2. LYMPHATIC SYSTEM STRUCTURE • Consists of : • lymph, • lymphatic vessels, • Lymph nodes • Other Lymph organs

3. Functions of the lymphatic system • Drain excess interstitial fluid and its return to the blood stream • Transport dietary lipid (in the villi of the small intestine) • Immune response function

4. Overview of the Lymphoid System • Organization of the Lymphoid System • Lymph • A fluid similar to plasma but does not have plasma proteins • Lymphatic vessels (lymphatics) • Carries lymph from peripheral tissues to the venous system • Lymphoid tissues and lymphoid organs • Lymphocytes, phagocytes, and other immune system cells

5. Overview of the Lymphoid System An Overview of the Lymphoid System.

6. Overview of the Lymphatic System • The Lymphatic System • Protects us against disease • Lymphoid system cells respond to • Environmental pathogens • Toxins • Abnormal body cells, such as cancers

7. Lymph vessels • Closely associated with the circulatory system vessels. • Larger lymph vessels are similar to veins. • Lymph capillaries are scatted throughout the body. • Contraction of skeletal muscle causes movement of the lymph fluid through valves.

8. Lymph vessels • Lymphatic Vessels • Are vessels that carry lymph • Lymphoid system begins with smallest vessels • Lymphatic capillaries (terminal lymphatics)

9. Lymph vessels • Lymphatic Capillaries • Differ from blood capillaries in four ways • Start as pockets rather than tubes • Have larger diameters • Have thinner walls • Flat or irregular in section

10. Lymph vessels • Function of the Lymphoid System • To produce, maintain, and distribute lymphocytes

11. Lymph vessels • Lymphocyte Circulation • From blood to interstitial fluid through capillaries • Returns to venous blood through lymphatic vessels • Lymph = interstitial fluid that has entered a lymphatic • The Circulation of Fluids • From blood plasma to lymph and back to the venous system • Transports hormones, nutrients, and waste products

12. Lymph vessels • Lymphocyte Production • Lymphocytes are produced • In lymphoid tissues (e.g., tonsils) • Lymphoid organs (e.g., spleen, thymus) • In red bone marrow • Lymphocyte distribution • Detects problems • Travels into site of injury or infection

13. Lymph vessels Lymphoid Capillaries.

14. Lymph vessels • Lymphatic Capillaries • Endothelial cells loosely bound together with overlap • Overlap acts as one-way valve • Allows fluids, solutes, viruses, and bacteria to enter • Prevents return to intercellular space

15. Lymph vessels • Lymph Flow • From lymphatic capillaries to larger lymphatic vessels containing one-way valves • Lymphatic vessels travel with veins • Lacteals • Are special lymphatic capillaries in small intestine • Transport lipids from digestive tract

16. Lymph vessels • Major Lymph-Collecting Vessels • The base of the thoracic duct • Expands into cisterna chyli • Cisterna chyli receives lymph from • Right and left lumbar trunks • Intestinal trunk

17. Lymph vessels • The Inferior Segment of Thoracic Duct • Collects lymph from • Left bronchiomediastinal trunk • Left subclavian trunk • Left jugular trunk • Empties into left subclavian vein

18. Lymph vessels • The Right Lymphatic Duct • Collects lymph from • Right jugular trunk • Right subclavian trunk • Right bronchiomediastinal trunk • Empties into right subclavian vein

19. Relationship of the Lymphatic System to the Cardiovascular System

20. Lymph vessels • Lymphedema • Blockage of lymph drainage from a limb • Causes severe swelling • Interferes with immune system function

21. Lymph organs • Lymph organs include the • bone marrow, • lymph nodes,  • spleen • thymus.

22. Lymph organs Lymphoid Tissues Connective tissues dominated by lymphocytes Lymphoid Nodule Areolar tissue with densely packed lymphocytes Germinal center contains dividing lymphocytes

23. Lymph organs Lymphoid Nodules.

24. Lymph organs Lymphoid Nodules.

25. Lymph organs Distribution of Lymphoid Nodules Lymph nodes Spleen Respiratory tract (tonsils) Along digestive and urinary tracts

26. Lymph organs Mucosa-Associated Lymphoid Tissue (MALT) Lymphoid tissues associated with the digestive system Aggregated lymphoid nodules Clustered deep to intestinal epithelial lining Appendix (or vermiform appendix) Contains a mass of fused lymphoid nodules

27. Lymph organs Lymphoid Organs Lymph nodes Thymus Spleen Are separated from surrounding tissues by a fibrous connective tissue capsule

28. Lymph organs Lymph Node A filter Purifies lymph before return to venous circulation Removes Debris Pathogens 99% of antigens

29. Lymph organs Lymphoid Functions Lymphoid tissues and lymph nodes Distributed to monitor peripheral infections Respond before infections reach vital organs of trunk

30. Lymph organs Lymph Nodes of Gut, Trachea, Lungs, and Thoracic Duct Protect against pathogens in digestive and respiratory systems

31. Lymph organs Lymph Nodes (Glands) Large lymph nodes at groin and base of neck Swell in response to inflammation Lymphadenopathy Chronic or excessive enlargement of lymph nodes may indicate infections, endocrine disorders, or cancer

32. Lymph organs The Thymus Located in mediastinum Atrophies after puberty Diminishing effectiveness of immune system

33. Lymph organs Three Functions of the Spleen Removal of abnormal blood cells and other blood components by phagocytosis Storage of iron recycled from red blood cells Initiation of immune responses by B cells and T cells In response to antigens in circulating blood

34. Lymph organs The Spleen.

35. OVERVIEW OF THE IMMUNE SYSTEM • The Immune System • Immunity • The ability to resist infection and disease • All body cells and tissues involved in production of immunity • Not just lymphoid system

36. Overview of the IMMUNE SYSTEM • Pathogens • Microscopic organisms that cause disease • Viruses • Bacteria • Fungi • Parasites • Each attacks in a specific way

37. Immunity • The immune response includes both specific and nonspecific components • 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.

38. The immune system is associated with defense against disease-causing agents, problems in transplants and blood transfusions, and diseases resulting from over-reaction (autoimmune, allergies) and under-reaction (AIDS).

39. Overview of the IMMUNE SYSTEM • Specific Defenses • Antibody-mediated and cell-mediated responses are two types of specific response.  • Lymphocytes • Part of the immune response • Identify, attack, and develop immunity: to a specific pathogen • Has a memory component that improves response time when an invader of the same type (or species) is again encountered.

40. Overview of the IMMUNE SYSTEM • Nonspecific Defenses • Nonspecific responses block the entry and spread of disease-causing agents. • Cannot distinguish one attack from another

41. Lymphocytes • Make up 20–30% of circulating leukocytes • Most are stored, not circulating • lymphocytes arise from by mitosis of stem cells in the bone marrow. • Some lymphocytes migrate to the thymus and become T cells that circulate in the blood and are associated with the lymph nodes and spleen. • B cells remain in the bone marrow and develop before moving into the circulatory and lymph systems. B cells produce antibodies.

42. Types of White Blood Cells

43. Structures of Body Defenses • Three Classes of Circulating Lymphocytes • T cells • Thymus-dependent • B cells • Bone marrow-derived • NK cells • Natural killer cells

44. Structures of Body Defenses • T Cells • Make up 80% of circulating lymphocytes • Three Main Types of T Cells • Cytotoxic T cells • Helper T cells • Suppressor T cells

45. T LYMPHOCYTE Human T-lymphocyte (SEM x12,080)

46. Structures of Body Defenses • B Cells • Make up 10–15% of circulating lymphocytes • Differentiate (change) into plasma cells • Plasma cells • Produce and secrete antibodies (immunoglobulin proteins)

47. Structures of Body Defenses • Body defenses provide resistance to fight infection, illness, and disease • Two categories of defenses • Nonspecific defenses • Specific defenses • Nonspecific and specific defenses operate together to provide resistance to infection and disease

48. Structures of Body Defenses • Nonspecific Defenses • Always work the same way • Against any type of invading agent • Specific Defenses • Protect against specific pathogens • Depend on activities of lymphocytes • Specific resistance (immunity) • Develops after exposure to environmental hazards

49. Nonspecific Defenses • Seven major categories of nonspecific defenses • Physical barriers • Phagocytes • Immunological surveillance • Interferons • Complement • Inflammatory response • Fever

50. Physical barriers • Barriers to entry are the skin and mucous membranes. • Keep hazardous materials outside the body • The skin is a passive barrier to infectious agents such as bacteria and viruses. The organisms living on the skin surface are unable to penetrate the layers of dead skin at the surface. • Tears and saliva secrete enzymes that breakdown bacterial cell walls. • Skin glands secrete chemicals that retard the growth of bacteria. • Mucus membranes lining the respiratory, digestive, urinary, and reproductive tracts secrete mucus that forms another barrier.