Lymphatic System

1. Lymphatic System ST120: Concorde Career College

2. Lymphatic System Objectives: • Define the term lymph. • Describe the functions of the lymphatic system. • List and identify the structures of the lymphatic system and describe the function of each. • Identify the origin of lymph.

3. Lymphatic System Objectives: • Trace the flow of lymph through the body. • Describe the immune system and describe the immune response. • Describe the mechanism by which the immune system helps to maintain homeostasis.

4. Lymphatic System Objectives: • Describe common diseases, disorders, and conditions of the lymphatic system including signs and symptoms, diagnosis, and available treatment options. • Demonstrate knowledge of medical terminology related to the lymphatic system verbally and in the written form.

5. Lymphatic System Functions of the Lymphatic System • Removal of impurities • Lymphocyte processing

6. Lymphatic System • The lymphatic system parallels (same direction)the circulatory system • Lymph vessels return tissue fluid to the blood & protect the body against foreign material • The lymphatic system includes: • Lymph fluid • Lymph vessels • Lymph nodes • Spleen • Thymus • And tonsils

7. Lymph Fluid Lymph is the tissue fluid that enters and travels through the lymphatic vessels • Plasma flows out of blood capillaries into tissue spaces (interstitial fluid) – AKA Tissue fluid • Plasma diffuses out of the capillaries faster than it is reabsorbed, the remaining interstitial fluid is returned to the blood through the lymphatic system

8. Lymphatic Capillaries • Lymphatic Capillaries - Carry lymph and resemble blood capillaries • Lacteals - Specialized lymphatic capillaries that carry chyle

9. Lymph Vessels • Vessels of the lymphatic system start with the smallest blind (dead-ended) lymph capillaries • The walls of the lymphatic capillaries are a thin walled, single layer of loosely fit squamous epithelial cells making them highly permeable • Lymphatic capillaries join larger lymphatic arterioles that then join lymphatic arteries • Lymphatic vessels like the veins of the circulatory system have valves

10. Lymph Flow

11. Lymphatic System Relationship of Lymphatic Vessels to Circulatory System

12. Thoracic Duct • Lymph returns to the blood flow through the thoracic duct and the left subclavianvein • Lymph from the lower body returns through the thoracic duct • Cisterna chyli– dilation at the beginning of the thoracic duct (pouch-like structure) • Lymph from a portion of the upper body also empties into the thoracic duct superior to the cisternachyli • Lymph from the upper left quadrant empties into the subclavian vein • Two terminal vessels include: Right Lymphatic duct & thoracic duct

13. Lymphahtic Drainage

14. Lacteal • Found in the villi of the small intestine • Responsible for absorbing fat-soluble nutrients (fatty acids and vit. A,D,E & K) • Fats are absorbed by the lacteals as chylomicron • Chylomicron: combination of fatty acids and glycerol to form triglycerides

15. Lacteal

16. Lymph nodes and nodules • Lymph Node: small ball shaped organs of the lymphatic system • Lymph Nodules: groups of lymph cells located beneath the epithelial layer of mucus membranes (ex. Respiratory tract and digestive tract) • Peyer’s patches: lymphatic nodules of the ileum • Filters pathogens and foreign material before returning to blood • Monitor the level of body fluid • Hematopoietic function – produce lymphocytes, macrophages, and monocytes • Located throughout the body • Cervical • Axillary • Inguinal

17. Regional Lymph Nodes

18. Lymph node Hilus Afferent vessels x4 pg.261 A&P Efferent vessels x1 Capsule Germinal centers Sinuses Trabecula

19. Tonsils • Palatine Tonsils (throat) – located at each side of the oropharynx • Pharyngeal (Adenoids) – located on the posterior wall of the nasopharynx • Lingual Tonsils – located at the base of the tongue

20. Tonsils

21. Lymphedema • Abnormal accumulation of fluid in interstitial spaces • Causes: • Obstruction of a lymphatic vessel (tumors, inflammation) • Increased capillary BP • Abnormal uptake of fluid by the lymphatic capillaries due to trauma or surgical wound (often seen after mastectomy)

22. Lymphedema

23. Lymphedema

24. Terms • Lymphadenitis: inflammation of lymph node/vessels • Metastasis: is the spread of a disease from one organ or part to another non-adjacent organ or part, causing a new cancer site • Lymphadenopathy: Any disease that usually involves the lymph glands

25. Sentinel Lymph Node Biopsy • Method developed to determine if breast cancer has spread to lymph ducts or nodes in the axilla • Prevents the patient from having to undergo a lymph node dissection • Sentinel Node: first node the breast drains to Nuclear Medicine • A radioactive dye is injected into the area where the tumor is located as well as around the areola • Hours later photos will reveal the pathway used to exit the breast, this will reveal the sentinel node OR • Surgeon injects a blue dye into the breast that assists in visual of the nodes • Small incision is made in the axilla • A special probe picks up signals form the radioactive dye and gets “excited” when over an affected node • All blue and radioactive nodes are removed

28. Spleen • Highly vascular and friable (easily crumbled/delicate) • Located behind the stomach • Contains lymphoid nodules (white pulp) • Filters blood (red pulp) cleans out foreign materials/microorganisms • Stores blood (approximately 200 ml) aids in maintenance of BP during severe hemorrhage • Hematopoietic function: lymphocytes, monocytes, leukocytes, fixed plasma cells • In a fetus the spleen produces erethrocytes

29. Spleen Hilus Splenic artery Splenic vein

30. Spleen cont. • #1 organ injured in MVA’s (motor vehicle accidents) despite being protected by the lower ribs • Splenectomy: surgical removal of the Spleen

31. Lymphatic System Reticuloendothelial System • Responsible for destruction of obsolete RBCs, bacteria, cancer cells, and other potentially harmful foreign substances. • Utilizes monocytes distributed throughout the body such as Kupffer’s cells located in the liver

32. Thymus • Located in the mediastinum • Composed of two lateral lobes bound by a connective tissue capsule • Proper function dependent on thymosin • Produces T-cells important in cell mediated immunity

33. Thymus

34. Lymphatic System Lymphatic and Immune Systems • Thymus • Bone marrow • Spleen • Tonsils • Lymph nodes • Lymph capillaries • Lymph vessels • Lymphocytes • Lymph

35. Lymphatic System Immunologic Defenses • Provide the body with general defenses against disease. • Nonspecific Defenses • Specific Defenses

36. Lymphatic System Nonspecific Defenses • Chemical and Mechanical Barriers • Phagocytosis • Natural Killer Cells • Inflammation • Fever • Interferon

37. Lymphatic System Occurrence of Infection • Not every exposure to a pathogen results in infection. • Portal of Entry • Virulence • Toxins • Dose • Predisposition

38. Lymphatic System Barriers Against Infection • Chemical • Body secretions • Mechanical • Skin • Mucous membranes • Cilia

39. First Line of Defense • Our first line of defense against microbes include: • Skin • Mucous membranes • Secretions

40. Skin • Unbroken skin prevents microbes from entering the body (keratin) • Broken skin such as Burns, Cuts, Scratches open the doors for an invasion of microbes such as Staphylococcus aureus • Sweat glands and Sebaceous gland secrete acids that kill or inhibit the growth of bacteria on the skin

41. Mucous Membranes • Line tracts open to the exterior of the body (respiratory, digestive, urinary) • Goblet cells secrete mucous to line the membranes and “catch” microbes • Cilia catch and pass debris up to the pharynx to be expelled • Glands in the stomach produce highly acidic gastric juice that kills most bacteria • Helicobacter Pylori is an exception… can cause stomach and duodenal ulcers

42. Second Line of Defense • If pathogens penetrate the 1st line of defense they will encounter the body’s 2nd line of defense Circulatory and chemical defenses • Circulatory Defenses: • Phagocytes • Complement proteins • Iron • Fever • Inflammatory response • Interferons

43. Phagocytes • Leukocytes responsible for phagocytosis • Phagocytosis: the process of surrounding and ingesting another microbe • Granulocytes • Neutrophils – motile and effective phagocytes • Eosinophils – attach to parasites and secrete peroxide ions which kill them. Play a larger phagocytic role during allergic response • Basophils • Agranulocytes • Monocytes – enter body tissues and mature into stationary macrophages or travel through blood to infection site (wandering macrophages) • Kupffer cells (liver), microglia (brain) • Lymphocytes – are not phagocytes but are important in the immune response

44. Phagocytosis • Chemotaxis – chemicals attract phagocytes to injured tissues or bacteria • Adherence – antibody molecules secrete a serum protein that can coat a bacterial cell and promote attachment (opsonization) • Ingestion – phagocyte surrounds the microbe • Pseudopods: “false feet” that extent to cover a microbe • The resulting sac is called a Phagosome • Digestion – phagosome is moved into the cytoplasm (phagolysosome) and enzymes (from the lysosomes) destroy the bacteria • Degranulation – digestion process

45. Complement proteins • Group of 25-30 serum proteins found in blood plasma • Circulate inactive until needed in the antibody-antigen reaction • Activated Proteins: increase inflammatory response, assist in lysis of antigen, attracts phagocytes • Complement cascade: sequence of proteins “bore” holes into bacteria causing an accumulation of fluid that eventually ruptures the cell

46. Iron • Virulence of bacteria increases when free iron is present • Leukocytes: produce interleukin-1 (IL-1), stimulates the liver to store iron depriving bacteria of necessary free iron

47. Inflammatory response • Inflammation is a beneficial and necessary response to injury • The four signs of inflammation include: • Pain • Heat • Redness • Swelling • Three stages of inflammation include: • Vasodilatation • Phagocyte migration • Tissue repair

48. Inflammatory Response • Vasodilation: Increased blood flow to area and increased permeability of blood vessels • Histamine, kinins, and prostaglandins: chemicals released by damaged tissues responsible for vasodilatation

49. Fever • An abnormally elevated body temperature (controlled by hypothalamus) • Systemic response frequently caused by viral or bacterial invasion • Symptoms include heat, shivering and increased metabolism rate • Vasodilatation and sweating signify the temperature falling “ fever breaking”

50. Interferons- produced by T-cells • Released to protect other cells by interferring with the ability of the virus to reproduce as it moves from cell to cell • Proteins produced by leukocytes, T-lymphocytes, and fibroblasts in response to infection “interfere with viral replication” • Proteins enter surrounding cells and inhibit the synthesis of proteins needed by invading viruses for multiplication • They interfere with viral replication Pg. 269 A&P