The lymphatic system consists of lymphatic vessels, lymph nodes, and organs that work together to drain excess fluid from tissues, absorb fatty acids, and fight infection. Lymphatic vessels carry lymph fluid unidirectionally towards the heart. Lymph nodes filter the lymph and contain immune cells that fight pathogens. Other lymphoid organs include the spleen, thymus, tonsils, and Peyer's patches. The immune system provides specific defense against pathogens through humoral and cellular responses involving B cells, T cells, antibodies, and memory cells. Disorders can result from immune deficiencies or autoimmunity.

1. LYMPHATIC SYSTEM
RIO D. DOMALAON,RN,MAN,JD

3. LYMPH NODES

4. THE LYMPHATIC SYSTEM
 Two parts
 Lymphatic vessels
 Lymphoid tissues and organs
 Lymphatic system functions
 Transport fluids back to the blood
 Play essential roles in body defense and resistance to
disease
 Absorb digested fat at the intestinal villi

5. LYMPHATIC CHARACTERISTICS
 Lymph – excess tissue fluid carried by lymphatic vessels
 Properties of lymphatic vessels
 One way system toward the heart
 No pump
 Lymph moves toward the heart
 Milking action of skeletal muscle
 Rhythmic contraction of smooth muscle in vessel walls

6. LYMPHATIC VESSELS

7. LYMPHATIC VESSELS
 Lymphatic
collecting vessels
 Collects lymph from
lymph capillaries
 Carries lymph to
and away from
lymph nodes

8. LYMPHATIC VESSELS
 Lymphatic collecting
vessels (continued)
 Returns fluid to
circulatory veins near
the heart
 Right lymphatic duct
 Thoracic duct

9. LYMPH
 Materials returned to the blood
Water
Blood cells
Proteins

10. LYMPH
 Harmful materials that enter lymph vessels
Bacteria
Viruses
Cancer cells
Cell debris

11. LYMPH NODES
 Filter lymph before it is returned to the blood
 Defense cells within lymph nodes
 Macrophages – engulf and destroy foreign
substances
 Lymphocytes – provide immune response to
antigens

12. LYMPH NODES

13. LYMPH NODE STRUCTURE

14. OTHER LYMPHOID ORGANS
 Several other organs
contribute to lymphatic
function
 Spleen
 Thymus
 Tonsils
 Peyer’s patches

15. THE SPLEEN
 Located on the left side of the abdomen
 Filters blood
 Destroys worn out blood cells
 Forms blood cells in the fetus
 Acts as a blood reservoir

16. THE THYMUS
 Located low in the throat, overlying the heart
 Functions at peak levels only during childhood
 Produces hormones (like thymosin) to
program lymphocytes

17. TONSILS
 Small masses of lymphoid tissue around the
pharynx
 Trap and remove bacteria and other foreign
materials
 Tonsillitis is caused by congestion with
bacteria

19. PEYER’S PATCHES
 Found in the wall of the
small intestine
 Resemble tonsils in
structure
 Capture and destroy
bacteria in the intestine

20. Mucosa-Associated Lymphatic Tissue (MALT)
 Includes:
 Peyer’s patches
 Tonsils
 Other small accumulations of lymphoid tissue
 Acts as a guard to protect respiratory and
digestive tracts

21. BODY DEFENSES
 The body is constantly in contact with bacteria, fungi, and
viruses (pathogens)
 The body has two defense systems for foreign materials
 Nonspecific defense system
 Mechanisms protect against a variety of invaders
 Responds immediately to protect body from foreign
materials

22. BODY DEFENSES
Specific defense system
Specific defense is required for each type
of invader
Also known as the immune system

23. NON-SPECIFIC BODY DEFENSES
 Body surface coverings
Intact skin
Mucous membranes
 Specialized human cells
 Chemicals produced by the body

24. SURFACE MEMBRANE BARRIERS –
First Line of Defense
 The skin
Physical barrier to foreign materials
pH of the skin is acidic to inhibit bacterial growth
Sebum is toxic to bacteria
Vaginal secretions are very acidic

25. SURFACE MEMBRANE BARRIERS –
First Line of Defense
 Stomach mucosa
 Secretes hydrochloric acid
 Has protein-digesting enzymes
 Saliva and lacrimal fluid contain lysozyme
 Mucus traps microoganisms in digestive and
respiratory pathways

26. DEFENSIVE CELLS
 Phagocytes
(neutrophils and
macrophages)
 Engulfs foreign
material into a vacuole
 Enzymes from
lysosomes digest the
material

27. MACROPHAGE ATTACKING E.COLI

28. DEFENSIVE CELLS
 Natural killer
cells
 Can lyse and kill
cancer cells
 Can destroy
virus- infected
cells

30. INFLAMMATORY RESPONSE -
Second Line of Defense
 Triggered when body tissues are injured
 Produces four cardinal signs
 Redness (Rubor)
 Heat (Calor)
 Swelling (Tumor)
 Pain (Dolor)
 Results in a chain of events leading to protection and healing

31. FUNCTIONS OF INFLAMMATORY
RESPONSE
 Prevents spread of damaging agents
 Disposes of cell debris and pathogens
 Sets the stage for repair

32. STEPS IN THE INFLAMMATORY RESPONSE

33. ANTIMICROBIAL CHEMICALS
 Complement
 A group of at least 20
plasma proteins
 Activated when they
encounter and attach to
cells (complement
fixation)

34. ANTIMICROBIAL CHEMICALS
 Complement
(continued)
 Damage foreign
cell surfaces
 Will rupture or lyse
the foreign cell
membrane

36. ANTIMICROBIAL CHEMICALS
 Interferon
Secreted proteins of virus-infected cells
Bind to healthy cell surfaces to inhibit
viruses binding

37. Interferons are a family species-specific proteins synthesized by eukaryotic
cells in response to viruses and a variety of natural and synthetic stimuli. There
are several different interferons commonly used as therapeutics, termed
alpha, beta, and gamma. These peptides are used to treat hairy cell leukemia,
AIDS-related Kaposi's sarcoma, laryngeal papillomatosis, genital warts, and
chronic granulomatous disease. Side effects include black tarry stools, blood
in the urine, confusion, and loss of balance.

38. FEVER
 Abnormally high body temperature
 Hypothalamus heat regulation can be reset by pyrogens
(secreted by white blood cells)
 High temperatures inhibit the release of iron and zinc from
liver and spleen needed by bacteria
 Fever also increases the speed of tissue repair

39. SPECIFIC DEFENSE: THE IMMUNE SYSTEM-
Third Line Defense
 Antigen specific – recognizes and acts against
particular foreign substances
 Systemic – not restricted to the initial infection site
 Has memory – recognizes and mounts a stronger
attack on previously encountered pathogens

40. TYPES OF IMMUNITY
 Humoral immunity
Antibody-mediated immunity
Cells produce chemicals for defense
 Cellular immunity
Cell-mediated immunity
Cells target virus infected cells

41. ANTIGENS (NONSELF)
 Any substance capable of exciting the immune system and
provoking an immune response
 Examples of common antigens
 Foreign proteins
 Nucleic acids
 Large carbohydrates
 Some lipids
 Pollen grains
 Microorganisms

42. SELF-ANTIGENS
 Human cells have many surface proteins
 Our immune cells do not attack our own proteins
 Our cells in another person’s body can trigger an
immune response because they are foreign
Restricts donors for transplants

43. ALLERGIES
 Many small molecules (called haptens or incomplete
antigens) are not antigenic, but link up with our own
proteins
 The immune system may recognize and respond to a
protein-hapten combination
 The immune response is harmful rather than protective
because it attacks our own cells

46. CELLS OF THE IMMUNE SYSTEM
 Lymphocytes
 Originate from hemocytoblasts in the red bone marrow
 B lymphocytes become immunocompetent in the bone marrow
 T lymphocytes become immunocompetent in the thymus
 Macrophages
 Arise from monocytes
 Become widely distributed in lymphoid organ

47. ACTIVATION OF LYMPHOCYTES

48. Humoral (Antibody-Mediated) Immune
Response
 B lymphocytes with specific receptors bind to a specific
antigen
 The binding event activates the lymphocyte to undergo clonal
selection
 A large number of clones are produced (primary humoral
response)

49. Humoral (Antibody-Mediated) Immune
Response
 Most B cells become plasma cells
 Produce antibodies to destroy antigens
 Activity lasts for four or five days
 Some B cells become long-lived memory cells (secondary
humoral response)

50. Humoral Immune Response

51. ACTIVE IMMUNITY
 Your B cells
encounter
antigens and
produce
antibodies
 Active immunity
can be naturally
or artificially
acquired

52. PASSIVE IMMUNITY
 Antibodies are obtained from someone else
 Conferred naturally from a mother to her fetus
 Conferred artificially from immune serum or gamma
globulin
 Immunological memory does not occur
 Protection provided by “borrowed antibodies”

53. ANTIBODIES (IMMUNOGLOBULINS) Igs
 Soluble proteins secreted by B cells (plasma cells)
 Carried in blood plasma
 Capable of binding specifically to an antigen

54. ANTIBODY CLASSES
 Antibodies of each class have slightly different roles
 Five major immunoglobulin classes – (Do Not Need to
know!)
 IgM – can fix complement
 IgA – found mainly in mucus
 IgD – important in activation of B cell
 IgG – can cross the placental barrier
 IgE – involved in allergies

55. Cellular (Cell-Mediated) Immune Response
 Antigens must be presented by macrophages to an
immunocompetent T cell (antigen presentation)
 T cells must recognize nonself and self (double recognition)
 After antigen binding, clones form as with B cells, but different
classes of cells are produced

56. Cellular (Cell-Mediated) Immune Response

57. T CELL CLONES
 Cytotoxic T cells
Specialize in killing infected cells
Insert a toxic chemical (perforin)
 Helper T cells
Recruit other cells to fight the invaders
Interact directly with B cells

59. T CELL CLONES
 Suppressor T cells
 Release chemicals to suppress the activity of T and B cells
 Stop the immune response to prevent uncontrolled activity
 A few members of each clone are memory cells

60. SUMMARY OF THE IMMUNE RESPONSE

61. Organ Transplants and Rejection
 Major types of grafts
 Autografts – tissue transplanted from one site to another on
the same person
 Isografts – tissue grafts from an identical person (identical
twin)
 Allografts – tissue taken from an unrelated person
 Xenografts – tissue taken from a different animal species

62. Organ Transplants and Rejection
 Autografts and isografts are ideal donors
 Xenografts are never successful
 Allografts are more successful with a closer tissue match

63. Disorders of Immunity: Immunodeficiencies
 Production or function of immune cells or
complement is abnormal
 May be congenital or acquired
 Includes AIDS – Acquired Immune Deficiency
Syndrome

64. Disorders of Immunity: Autoimmune Diseases
 The immune system does not distinguish between self and
nonself
 The body produces antibodies and sensitized T lymphocytes
that attack its own tissues

65. Disorders of Immunity: Autoimmune Diseases
 Examples of autoimmune diseases
 Multiple sclerosis – white matter of brain and spinal cord
are destroyed
 Myasthenia gravis – impairs communication between
nerves and skeletal muscles
 Juvenile diabetes – destroys pancreatic beta cells that
produce insulin
 Rheumatoid arthritis – destroys joints

66. Disorders of Immunity: Autoimmune Diseases
 Examples of autoimmune diseases (continued)
 Systemic lupus erythematosus (SLE) – affects kidney,
heart, lung and skin
 Glomerulonephritis – impairment of renal function

67. Immune Deficiency: AIDS
HIV targets cells
Retrovirus attaches to CD4 receptors of
T helper cells
Transmission: Body fluids, i.e., blood, semen,
breast milk, vaginal secretions

68. STRUCTURE OF HIV

69. Time Course of the Progression of AIDS after
HIV Infection

70. AIDS progression:
Phase I: few weeks to a few years; flu like symptoms, swollen lymph
nodes, chills, fever, fatigue, body aches. Virus is multiplying,
antibodies are made but ineffective for complete virus removal
Phase II: within six months to 10 years; opportunistic infections
present, Helper T cells affected, 5% may not progress to next phase
Phase III: Helper T cells fall below 200 per cubic millimeter of blood
AND the person has an opportunistic infection or type of cancer.
Person is now termed as having “AIDS” May include pneumonia,
meningitis, tuberculosis, encephalitis, Kaposi’s sarcoma, and non-
Hodgkin’s lymphoma….


71. AIDS Pandemic
More than 36 million infected with HIV worldwide
Most infections in sub-Sahara of Africa
Increasing spread in Asia and India
Most often spread by heterosexual contact outside
U.S.

73. REFERENCES
Copyright © 2003 Pearson Education, Inc. publishing as
Benjamin Cummings
Marieb,E.N. (2019).Essentials of Human Anatomy and
Physiology.Jurong,Singapore:Pearson Education South Asia
Pte Ltd.
www.youtube.com