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Lymphatic and immune system
The document summarizes the lymphatic and immune systems. It describes the main structures of the lymphatic system as lymphatic vessels and lymph nodes. It then explains the main components of the immune system as lymphocytes, lymphoid tissue, and lymphoid organs. Finally, it discusses disorders that can affect these systems such as lymphangitis, mononucleosis, Hodgkin's disease, and non-Hodgkin's lymphoma.
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Lymphatic and immune system
- 1. IMMUNE SYSTEM PRESENTED BY: DR MARIAM ASIF
- 2. LYMPHATIC AND IMMUNE SYSTEM
- 3. The Lymphatic and Immune Systems • Main structures of the lymphatic system – Lymphatic vessels • Main components of the immune system – Lymphocytes – Lymphoid tissue – Lymphoid organs
- 4. The Lymphatic System • Lymphatic vessels collect tissue fluid from loose connective tissue – Carry fluid to great veins in the neck – Fluid flows only toward the heart Figure 20.1
- 5. Functions of LymphaticVessels • Collect excess tissue fluid and blood proteins • Return tissue fluid and blood proteins to bloodstream
- 6. Orders of LymphaticVessels • Lymph capillaries - smallest lymph vessels – first to receive lymph • Lymphatic collecting vessels – collect from lymph capillaries
- 7. Orders of LymphaticVessels • Lymph nodes – scattered along collecting vessels • Lymph trunks – collect lymph from collecting vessels • Lymph ducts – empty into veins of the neck
- 8. Lymphatic Capillaries • Locatednear blood capillaries • Receive tissue fluid from CT - increased volume of tissue fluid - minivalve flaps open and allow fluid to enter • Highly permeability allows entrance of – tissue fluid – bacteria, viruses, and cancer cells
- 9. Lymphatic Capillaries • Lacteals – specialized lymphatic capillaries - located in the villi of the small intestines - receive digested fats - fatty lymph – chyle
- 10. Lymphatic Capillaries Figure 20.2a, b
- 11. Lymphatic Collecting Vessels •Accompany blood vessels • Composed of the same three tunics as BVs • Contain more valves than veins do – helps direct the flow of blood • Lymph propelled by – bulging of skeletal muscles – pulsing of nearby arteries – tunica media of the lymph vessels
- 12. Lymph Nodes • Cleansethe lymph of pathogens • Human body contains around 500 • Lymph nodes are organized in clusters
- 13. Lymph Nodes Figure 20.3
- 14. Microscopic Anatomy of a Lymph Node • Fibrous capsule – surrounds lymph nodes • Trabeculae – connective tissue strands • Lymph vessels – Afferent lymphatic vessels – Efferent lymphatic vessels
- 15. Lymph Node Microscopic Anatomy Figure 20.4a
- 16. Lymph Trunks • Lymphaticcollecting vessels converge Five major lymph trunks: • Lumbar trunks - receives lymph from lower limbs • Intestinal trunk - receives chyle, digestive organs • Bronchomediastinal trunks - collects lymph from thoracic viscera • Subclavian trunks - receive lymph from upper limbs and thoracic wall • Jugular trunks - drain lymph from head & neck
- 17. Lymph Nodes, Trunks,and Ducts Figure 20.3
- 18. The Lymphatic Trunks Figure 20.6a
- 19. Lymph Ducts • Cisternachyli – located at the union of lumbar and intestinal trunks • Thoracic duct – Ascends along vertebral bodies – Empties into venous circulation – Junction of left internal jugular and left subclavian veins – Drains three quarters of the body • Right lymphatic duct – empties into right internal jugular and subclavian veins
- 20. The Immune System •Recognizes specific foreign molecules • Destroys pathogens effectively • Key cells – lymphocytes • Also includes lymphoid tissue and lymphoid organs
- 21. Lymphocytes • Infectious organismsattacked by inflammatory response – macrophages, then lymphocytes • Cytotoxic T lymphocytes – Attack foreign cells directly – Binds to antigen-bearing cells – Perforates cell membrane – Signals cell to undergo apoptosis
- 22. Lymphocytes • B lymphocytes - become plasma cells - secrete antibodies, mark cells for destruction by macrophages
- 23.
- 24. Lymphocyte Activation • Lymphocytesoriginate in bone marrow • T lymphocytes travel to the thymus gland • B lymphocytes stay in bone marrow • Able to recognize a unique antigen • Gain immunocompetence – travels through blood stream – meets and binds to a specific antigen
- 25. Lymphocyte Activation • ActivatingT or B cells produce – Effector lymphocytes • Short-lived, attack immediately – Memory lymphocytes • Wait until body encounters their antigen again – Basis of acquired immunity – Guard against subsequent infections
- 26.
- 27. Lymphoid Tissue • Mostimportant tissue of the immune system Two general locations: • Mucous membranes of digestive, urinary, respiratory, and reproductive tracts - Mucosa-associated lymphoid tissue (MALT) • Lymphoid organs (except thymus)
- 28. Lymphoid Organs • Primarylymphoid organs – Bone marrow – Thymus • Secondary lymphoid organs – Lymph nodes, spleen, tonsils – Aggregated lymphoid nodules – Appendix
- 29. Lymphoid Organs • Designed to gather, destroy infectious microorganisms Figure 20.10
- 30. Thymus • Immature lymphocytesdevelop into T lymphocytes - secretes thymic hormones - most active in childhood • Functional tissue atrophies with age - composed of cortex and medulla - medulla contains Hassall’s corpuscles (thymic corpuseles) • Differs from other lymphoid organs - functions strictly in lymphocyte maturation - arises from epithelial tissue
- 31. Thymus Figure 20.11
- 32. Lymph Nodes Functional pathway •Lymph percolates through lymph sinuses • Most antigenic challenges occur in lymph nodes • Antigens destroyed – activate B and T lymphocytes
- 33. Spleen • Largest lymphoidorgan • Two main blood-cleansing functions – Removal of blood-borne antigens – Removal and destruction of old or defective blood cells • Site of hematopoiesis in the fetus
- 34. Spleen • Destruction ofantigens • Site of B cell maturation into plasma cells • Phagocytosis of bacteria and worn-out RBCs, WBCs and platelets • Storage of platelets
- 35. • White pulp– thick sleeves of lymphoid tissue • Red pulp - surrounds white pulp - composed of venous sinuses - splenic cords
- 36. Spleen Figure 20.12
- 37. Tonsils • Simplest lymphoidorgans • Four groups of tonsils – palatine, lingual, pharyngeal, and tubal tonsils • Arranged in a ring to gather and remove pathogens • Underlying lamina propria consists of MALT
- 38. Palatine Tonsil Figure 20.13
- 39. Aggregated Lymphoid Nodules and Appendix • MALT – abundant in walls of intestines • Fight invading bacteria • Generate a wide variety of memory lymphocytes - aggregated lymphoid nodules (Peyer’s patches) - located in the distal part of the small intestine • Appendix – tubular offshoot of the cecum
- 40. Aggregated Lymphoid Nodule Figure 20.14
- 41. Disorders of theLymphatic and Immune Systems • Chylothorax - leakage of fatty lymph into the thorax • Lymphangitis - inflammation of a lymph vessel • Mononucleosis - caused by Epstein-Barr virus - attacks B lymphocytes • Hodgkin’s disease - malignancy of lymph nodes • Non-Hodgkin’s lymphoma - uncontrolled multiplication - metastasis of undifferentiated lymphocytes
- 42. The Lymphatic andImmune Systems Throughout Life • Lymphatic vessels and lymph nodes – develop from lymphatic sacs • Thymus originates as an outgrowth of endoderm • Spleen, lymph nodes, and MALT – arise from mesodermal mesenchyme