LYMPHATIC SYSTEM & IMMUNITY

1. LYMPHATIC SYSTEM& IMMUNITY

2. Lymphatic system structure and function Lymphatic system consists • lymph • structures and organs containing lymphatic tissue, red bone marrow • lymphatic vessels

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

4. Lymph • Lymph is a clear to yellowish watery fluid which is found throughout the body. • It circulates through body tissues picking up fats, bacteria, and other unwanted materials, filtering these substances out through the lymphatic system.

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

6. Lymph vessels • Lymphatic Vessels • Are vessels that carry lymph • Closely associated with the circulatory system vessels • Lymphoid system begins with smallest vessels • Lymphatic capillaries (terminal lymphatics) • Lymph capillaries are scatted throughout the body

7. Lymph vessels • Larger lymph vessels are similar to veins. • Lymphatic vessels travel with veins • Lymph Flow • From lymphatic capillaries to larger lymphatic vessels containing one-way valves • Contraction of skeletal muscle causes movement of the lymph fluid through valves

8. The Circulation of Lymph • Lymph = interstitial fluid that has entered a lymphatic • From blood plasma to lymph and back to the venous system • Transports hormones, nutrients, and waste products

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

10. Lymphatic Capillaries • 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

11. Lymphatic Capillaries

12. Lymphatic Capillaries Lacteals Are special lymphatic capillaries in small intestine Transport lipids from digestive tract

13. The Circulation of Lymph • 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

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

15. The Circulation of Lymph • The Right Lymphatic Duct Collects lymph from • Right jugular trunk • Right subclavian trunk • Right bronchiomediastinal trunk • Empties into right subclavian vein

16. Relationship of the Lymphatic System to the Cardiovascular System

17. What Is Lymphedema? • Lymphedema is an abnormal buildup of fluid that causes swelling, most often in the arms or legs. • The condition develops when lymph vessels or lymph nodes are missing, impaired, damaged, blocked or removed • Eg- Following radical mastectomy

18. Lymphedema

19. Structures of Body Defenses • Lymphoid Functions • Lymphoid tissues and lymph nodes • Distributed to monitor peripheral infections • Respond before infections reach vital organs of trunk

20. Structures of Body Defenses • Lymphoid Tissues • Connective tissues dominated by lymphocytes • Lymphoid Nodule • Areolar tissue with densely packed lymphocytes • Germinal center contains dividing lymphocytes

21. 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.

22. Lymphocytes • Lymphocyte Production • 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 • Lymphocyte Circulation • From blood to interstitial fluid through capillaries • Returns to venous blood through lymphatic vessels

23. Lymphocytes • Three Classes of Circulating Lymphocytes • T cells • Thymus-dependent • B cells • Bone marrow-derived • B cells produce antibodies. • NK cells • Natural killer cells

24. T Lymphocytes • Make up 80% of circulating lymphocytes • Three Main Types of T Cells • Cytotoxic T cells • Helper T cells • Suppressor T cells

25. B Lymphocytes • Make up 10–15% of circulating lymphocytes • Differentiate (change) into plasma cells • Plasma cells • Produce and secrete antibodies (immunoglobulin proteins)

26. Lymphoid Organs/Nodules • Lymph Nodes of Gut, Trachea, Lungs, and Thoracic Duct and urinary tracts • Thymus • Spleen • Protect against pathogens in digestive and respiratory systems • Are separated from surrounding tissues by a fibrous connective tissue capsule

27. Tonsils

28. Structures of Body Defenses • 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

29. Structures of Body Defenses Lymphoid Nodules.

30. Structures of Body Defenses • Lymph Node • A filter • Purifies lymph before return to venous circulation • Removes • Debris • Pathogens • 99% of antigens

31. Lymph nodes

32. Lymph nodes • Lymph Nodes (Glands) • Large lymph nodes at groin and base of neck • Swell in response to inflammation

33. Structures of Body Defenses • Lymphadenopathy • Chronic or excessive enlargement of lymph nodes may indicate infections, endocrine disorders, or cancer Enlarged lymph nodes due to tuberculosis

34. Structures of Body Defenses • The Thymus • Located in mediastinum • Atrophies after puberty • Diminishing effectiveness of immune system

35. Structures of Body Defenses The Spleen • 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

36. Structures of Body Defenses The Spleen.

37. The Immune System • Immunity- the ability to resist infection and disease • 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).

38. Overview of the Lymphatic System • The Lymphatic System • Protects against disease • Lymphoid system cells respond to • Pathogens • Toxins • Abnormal body cells, such as cancers

39. Overview of the Lymphatic System Pathogens • Microscopic organisms that cause disease • Viruses • Bacteria • Fungi • Parasites • Each attacks in a specific way

40. Structures of Body Defenses • Body defenses provide resistance to fight infections and diseases • Two categories of defenses • Nonspecific defenses- are the first line of defense. • Specific defenses -the second line of defense and are tailored to an individual threat. • Nonspecific and specific defenses operate together to provide resistance to infection and disease

41. 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

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

43. 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.

44. 1. Physical barriers

45. 2. Phagocytes • Phagocytes • Attack and remove dangerous microorganisms • Microphages • Neutrophils and eosinophils • Leave the bloodstream • Enter peripheral tissues to fight infections Macrophage Attacking E.coli 

46. 3. Interferons • Chemical messengers that trigger production of antiviral proteins in normal cells • Antiviral proteins • Do not kill viruses • Block replication in cell

47. Interferons • Three Types of Interferons • Alpha-interferons • Produced by leukocytes • Stimulate NK cells • Beta-interferons • Secreted by fibrocytes • Slow inflammation • Gamma-interferons • Secreted by T cells and NK cells • Stimulate macrophage activity

48. 4. Complement (C) Proteins • Form the complement system • Complement the action of antibodies • Produced in the liver become active in a sequence (C1 activates C2, etc.) • The complement system proteins bind to a bacterium and open pores in its membrane through which fluids and salt move, swelling and bursting the cell.

49. Complement (C) Proteins

50. Complement (C) Proteins The complement system of proteins and their functioning