1. The Body’s Defense Systems
The Lymphatic and Immune Systems
The Body’s Defense Systems

2. Learning Outcomes
32.1 List the pathways and organs of the lymphatic system and give their locations.
31.2 Define lymph and tell how it is circulated in the body.
31.3 Define the terms infection, pathogen, and antigen.
31.4 List and describe the nonspecific body defense mechanisms.
31. 5 Explain the signs and causes of inflammation.

3. Learning Outcomes (cont.)
32.6 Explain what is meant by body defenses.
32.7 Define B cells and T cells and describe their locations and functions.
Explain the importance of MHC proteins.
List the different types of T cells and describe their functions.
32.10 Explain how antibodies fight infection.

4. Learning Outcomes (cont.)
32.11 List the different types of antibodies and tell how they differ.
32.12 Define complement proteins and give their function.
32.13 Explain the difference between the primary immune response and secondary immune response.
32.14 Explain the four different types of acquired immunities.
32.15 Describe the function of a vaccine.

5. Learning Outcomes (cont.)
32.16 Define the terms cancer and carcinogen.
32.17 Describe how cancers are diagnosed and treated.
Explain how cancers are classified.
32.19 Describe how allergies develop.
32.20 Describe the causes, signs and symptoms, and treatments of other common immune disorders.

6. Introduction Immune system Lymphatic system Protects the body against
Bacteria
Viruses
Fungi
Toxins
Parasites
Cancer
Lymphatic system
Works with immune system to remove disease-causing agents
Organs
Thymus
Spleen
Lymph nodes

7. The Lymphatic System Network of connecting vessels
Collects fluid (lymph) between cells and returns it to bloodstream
Picks up lipids from digestive organs and transports them to blood stream
Functions to defend the body against pathogens

8. Lymphatic System: Pathways
Lymphatic capillaries
Extend into interstitial spaces (between cells)
Permeable, thin walls pick up fluid, now lymph
Delivers lymph to lymphatic vessels
Lymphatic vessels
Deliver lymph to lymph nodes
Cells in nodes can remove pathogens from lymph and start an immune response
Leaves nodes through efferent lymphatic vessels
Lymph System

9. Lymphatic System: Pathways (cont.)
Lymphatic trunks
Receive lymph from efferent lymphatic
vessels
Deliver it to
Lymphatic collecting ducts
Thoracic duct
Left side of head and neck, left arm, left side of thorax, entire abdominopelvic area, and both legs
Right lymphatic duct
Right side of head and neck, right arm, and right side of chest
Lymph System

10. Lymphatic System: Tissue Fluid and Lymph
Interstitial fluid
Fluid in spaces between cells that has leaked from blood capillaries and has not been picked up by body cells
High in nutrients, oxygen, and small proteins
Becomes lymph
Pushed through lymphatic vessels by squeezing action of neighboring skeletal muscles and breathing movement

11. Back

12. Lymphatic System: Nodes
Small, glandular structures
Located along paths of larger lymphatic vessels
Afferent lymphatic vessels – Lymph to node
Efferent lymphatic vessels – node to Lymph

13. Lymphatic System: Nodes (cont.)
More lymph enters than can leave at one time
Cells in nodes
Macrophages – digest unwanted pathogens
Lymphocytes – start an immune response against pathogen
Nodes can generate some lymphocytes

14. Lymphatic System: The Thymus and Spleen
Soft, bi-lobed organ
Located just above the heart in the mediastinum
Large in children, shrinks as we age
Functions
Same as lymph nodes
Also produces lymphocytes
Produces thymosin – stimulates production of lymphocytes

15. Lymphatic System: The Thymus and Spleen (cont.)
Largest lymphatic organ
Located in the upper left quadrant of abdominal cavity
Functions
Filters blood similarly to lymph nodes
Removes worn-out red cells
If removed (splenectomy), liver takes over most of its function

16. Apply Your Knowledge Correct!
What are the lymphatic collecting ducts and what area do they drain?
ANSWER: The collecting ducts are:
Thoracic duct, which drains the left side of the head and neck, left arm, left side of thorax, entire abdominopelvic area, and both legs; and the right lymphatic duct, which drains the right side of the head and neck, right arm, and right side of the chest.
Correct!

17. Defenses Against Disease
Infection
The presence of a pathogen in or on the body
Pathogen
A disease-causing agent
Antigen
Anything foreign
Innate immunity
Nonspecific defenses to protect against pathogens
Nonspecific defenses
Species resistance
Mechanical barriers
Chemical barriers
Phagocytosis
Fever
Inflammation

18. Defenses Against Disease: Specific Defenses
Immunities
Protect against very specific pathogens
Substances involved
Proteins – antibodies
WBCs – lymphocytes and macrophages
Lymph system
Cytokines – assist in immune response regulation

19. Defenses Against Disease (cont.)
Two major types of lymphocytes
B Cells and T Cells
Response
Recognize antigens in the body
B cells
Made in bone marrow
Humoral response
Respond to antigens by becoming plasma cells
Plasma cells make antibodies
Memory B cells produce stronger response with next exposure to antigen
T Cells
Matured in Thymus gland
Cell-mediated response
Bind to antigens on cells and attack them directly
Secrete lymphokines that increase T cell production and directly kill infected cells

20. Defenses Against Disease (cont.)
Helper-T cell activation
Begins when macrophage ingests and digests pathogen with antigen on it
Antigens are placed on cell membrane of macrophage
T cell recognizes and binds to antigen
Now can divide to form other types of T cells
Aka. Killer T cells

21. Defenses Against Disease (cont.)
Types of T cells
Cytotoxic (Killer) T cells
Protect body against viruses and cancer cells
Helper T cells
Increase antibody formation, memory cell formation, B cell formation, and phagocytosis
Memory T cells
Remember the pathogen that activated original T cell
Later exposures trigger an immune response more effective than initial response

22. Defenses Against Disease (cont.)
Natural killer (NK) cells
Type of lymphocyte
Primarily target cancer cells
Kill on contact
Do not recognize a specific antigen

23. Apply Your Knowledge Right on Target! ANSWER:
Identify whether each item refers to T cells, B cells, or NK cells:
___ Primarily target cancer cells
___ Respond to antigens by becoming plasma cells
___ Must be activated to respond to an antigen
___ Bind to antigens on cells and attack them directly
___ Kill on contact
___ Need macrophages and MHC for activation
___ Make antibodies against specific antigen
Right on Target!

24. Antibodies
Also called immunoglobulins (don’t need to know specific kinds)
IgA
Prevents pathogens from entering body
IgD
Found on B cell membranes
Thought to control B cell activity
IgE
Found with IgA
Involved in triggering allergic reactions

25. Antibodies (cont.) IgG IgM Recognizes bacteria, viruses, and toxins
Activates complements
IgM
Large and binds to antigens on food, bacteria, or incompatible blood cells
Activates compliments

26. Antibodies (cont.) Actions that occur when antibodies bind to antigens
Allow phagocytes to recognize and destroy antigens
Cause antigens to clump together, causing them to be destroyed by macrophages
Cover the toxic portions of antigens, making them harmless
Activate complement
Group of proteins in serum that attack pathogens by forming holes in them
Attract macrophages to pathogens and can stimulate inflammation

27. Apply Your Knowledge
What are the possible actions that occur when antibodies bind to antigens?

28. Immune Responses and Acquired Immunity
Primary immune response occurs with first exposure to antigen
Slow process
Memory cells are formed
Secondary immune response with next exposure to same antigen
Quick and carried out by memory cells
Usually prevents person from developing disease from the antigen

29. Immune Responses and Acquired Immunity (cont.)
Naturally acquired active immunity
Natural exposure to antigen – having an illness
Makes antibodies and memory cells
Long-lasting
Artificially acquired active immunity
Injected with pathogen – immunizations

30. Immune Responses and Acquired Immunity (cont.)
Naturally acquired passive immunity
Acquired from mother
Breast milk
Placenta
Short-lived
Artificially acquired passive immunity
Injected with antibodies (such as antivenom)

31. Apply Your Knowledge Good Answer!
After you give an immunization to a 2-year-old, her mother asks you why this will work to prevent her from getting a disease.
Good Answer!

32. Major Immune System Disorders
Cancer
Uncontrolled growth of abnormal cells form malignant tumors
200 known types
Treatment based on stage
0 – very early; cancer cells localized
I – spread to deeper layers or some in surrounding tissues
II – spread to surrounding tissues but contained in primary site
III – spread beyond primary site into nearby areas
IV – spread to other organs
Recurrent – reappeared after treatment

33. Major Immune System Disorders (cont.)
Allergies
Immune response to an allergen
Can be excessive
IgE antibodies bind to allergens and stimulate mast cells to release histamine and heparin
Triggers allergic response
Allergy shots
Small amounts of allergen stimulates production of IgG to prevent IgE from binding to antigen
IgG antibodies do not stimulate mast cells, so immune response is not generated

34. Major Immune System Disorders (cont.)
Signs/symptoms
Inhaled allergens – runny nose, sneezing, coughing, wheezing
Ingested allergens – nausea, vomiting, diarrhea
Skin allergens – rashes
Allergens in blood – most life-threatening; can affect many organs
Treatment
Antihistamines, decongestants – OTC or prescription
Epinephrine for anaphylaxis – vasoconstriction, increasing BP
Anaphylaxis – life-threatening response

35. Common Immune System Disorders
Autoimmune disease
Body attacks itself
Examples
Scleroderma
Rheumatoid arthritis
Multiple sclerosis
Glomerulonephritis
Chron’s disease
Diabetes mellitus, type I

36. Common Immune System Disorders (cont.)
Description
AIDS
Development of severe signs and symptoms caused by HIV as it destroys lymphocytes; leaves immune system weakened and susceptible to other diseases
Chronic fatigue syndrome (CFS)
Condition of severe tiredness not relieved by rest and not related to other illnesses
Lymphedema
Blockage of lymphatic vessels results in tissue swelling that increases over time

37. Common IS Disorders (cont.)
Description
Mononucleosis
“Mono”; highly contagious viral infection spread through saliva of infected person
Systemic lupus erythematous (SLE)
Autoimmune disorder; antibodies produces that target own cells and tissues; affects women more often than men

38. Apply Your Knowledge Excellent! ANSWER: Matching:
___ Immune response to a substance A. CFS
___ Blockage of lymphatic vessels B. SLE
___ “Kissing disease” C. Cancer
___ “Butterfly” rash on face D. Autoimmune disease
___ Severe tiredness E. Lymphedema
___ Uncontrolled growth of abnormal cells F. Mononucleosis
___ Body attack its own antigens G. Allergy

39. In Summary Immune system is the body’s major line of defense
Primary function – protect against infection, toxins, and cancer
Specific or nonspecific defenses
Lymphocytes are major cells of immune system
Immune response may be primary or secondary
Medical assistant must understand immune system
Aseptic technique
Infection control
Educate patients

40. End of Chapter
End of Chapter 32
Thought is an infection. In the case of certain thoughts, it becomes an epidemic.
~Wallace Stevens