1. and Immune System

2. LYMPHATIC SYSTEM FUNCTIONS
Production, maintenance & distribution of lymphocytes
Return of fluid & solutes from peripheral tissues to blood
Distribution of hormones, nutrients & products from point of origin to general circulation

4. LYMPH CIRCULATION Arteries Capillaries Fluid exits circulation Heart
Veins
Capillaries
Fluid exits
circulation

5. Lymphatic Vessels Collect fluid from around tissues1 2 3 4
Collect fluid from around tissues
Transports fluid & solutes back to venous
circulation
Fluid moves from tissues into lymph capillaries; becomes lymph
Lymph capillaries converge to form lymphatic vessels
Lymph passes through lymph nodes
Lymphatic vessels converge into larger vessels; valves prevent backflow 1

6. Lymphatic System Components
Tonsils
Lymphoid nodules (no capsule)
Guard entrance to digestive & respiratory tracts
Lymph Nodes
Filter & purifies lymph
Removes abnormal & foreign cells
Surrounded by capsule
Lymphatic Vessels
Carry lymph back to venous

7. Thoracic duct (yellow)
Thymus
Thoracic duct (yellow)
Collects lymph from left side above diaphragm & whole body below diaphragm
Dumps lymph into venous circulation
Right lymphatic duct (orange)
Collects lymph from right side above diaphragm
Thymus
Site of T cell maturation

8. Spleen
Removes abnormal blood cells & components
Bone Marrow
Hemocytoblasts produce lymphoid stem cells
Lymphoid stem cells divide & differentiate into lymphocytes
Appendix
Contains lymphoid tissue

10. Immunity-Immune System
Innate
Immune defenses that are active immediately upon infection
Response is the same whether you have seen the pathogen before or not.
Adaptive
Acquired immunity
Activated in response to specific pathogens
Differs from one person to another
Slower than innate responses
Strong defense against specific pathogens
Ex. Vaccination (immunization)
Made of harmless part of disease-causing pathogen (dead or weakened virus, piece of virus, inactivated bacterial toxin, surface proteins of virus)
If you are exposed to what you have been vaccinated against, your immune system quickly responds.

11. Immunity Continued Active Passive
Immune system is actively producing antibodies
Passive
Receive “premade” antibodies
Mothers antibodies through placenta or via breast milk
Injection of antibodies
Ex injection a snakebite victim with antivenom
(extracted from animals previously immunized against the venom)
Temporary immunity
Recipients immune system is not
stimulated by antigens
Lasts only as long as antibodies
do (few weeks or months)

12. Lymphocytes Production
Hemocytoblasts in bone marrow produce lymphoid stem cells
Some stem cells remain in bone marrow & divide to produce B cells, T cells, & NK cells

13. B Cells Responsible for antibody-mediated immunity Lymphocytes
10 – 15% of circulating lymphocytes
When activated divide & differentiate into:
Plasma cells
Memory B cells
Responsible for antibody-mediated immunity

14. Natural Killer cells Lymphocytes 5 to 10% circulating
• Responsible for cell-mediated immunity
Attack foreign & abnormal cells
Responsible for immunological surveillance
Lyse and kill cancer cells and virus-infected cells.

15. T Cells Responsible for cell-mediated immunity
Some stem cells migrate to thymus & divide to produce T cells
T Cells
Lymphocytes
Thymus
80% of circulating lymphocytes
When activated divide and differentiate into:
Helper T cells
Cytotoxic T cells
Memory T cells
Suppressor T cells
Responsible for cell-mediated immunity

17. NONSPECIFIC DEFENSES Does not discriminate pathogens
Present at birth (innate)
Prevents approach or entry of pathogens

18. Skin
Creates effective barrier (multiple layers, keratin coating, desmosomes hold cells tog.)
Hairs (provide some protection against abrasion, keep hazardous materials & insects from contacting skin
Secretions (oil, sweat & mucus): wash away pathogens & materials, contain chemicals that kill bacteria (lysozymes

19. Phagocytes Engulf & destroy pathogens & debris
Neutrophil
-Macrophage
-Phagocytize cellular debris & invading bacteria
Eosinophil
-Target foreign compounds or pathogens coated with antibodies
Macrophage
-Derived from monocytes
-Large, active phagocytes

21. Immunological surveillance
Destroys abnormal cells
Constant monitoring of normal tissues
Involves NK (natural Killer) cells
NK cells sensitive to antigens characteristic of abnormal cell membranes.

22. INTERFERONS Small proteins
Released by activated lymphocytes, macrophages & virus infected cells
Increases resistance of other cells to viral infections

23. COMPLEMENT SYSTEM
Several proteins that interact in chain reaction (cascade)
Attacks & breaks down cell walls
Attracts phagocytes
Stimulates inflammation

24. INFLAMMATORY RESPONSE
Mast Cells (and Basophils) release histamines
Increases blood flow
Activates phagocytes
Increase capillary permeability
Increases temperature
Stimulates clotting
Activates complement
Activates specific immune responses

26. FEVER Body temperature rises above 37.2 oC (99 oF)
Pyrogens – proteins that increase body temperature
Mobilizes defenses
Accelerates repair

27. What about allergies?

28. SPECIFIC DEFENSES

29. PROPERTIES OF IMMUNITY
Specificity
Specific defense activated by antigen
Targets only that antigen
Versatility
Immune system produces millions of different lymphocytes
Each lymphocyte has different antigen receptors
Memory
• Immune system remembers antigens it has encountered
Tolerance
When immune system does not respond to particular antigen
Immune system ignores normal (self) & attacks foreign (nonself)

30. Cell-Mediated Immunity
Provides defense against abnormal cells & pathogens that are inside living cells
Involves T cells

31. Cytotoxic T cells Memory T cells Helper Suppressor T cells Macrophage•
Engulfs antigen
Breaks down antigen
Presents antigen
fragment on surface
of cell membrane
Specific T cell activated
when contacts
macrophage with antigen
Activated T cell divides
& differentiates
Cytotoxic
T cells
Memory T cells
Helper
Suppressor T cells

33. Antibody-mediated immunity (humoral)
Provides defense against antigens & pathogens in body fluids
Involves B cells

34. Helper T cell activates specific B cell by secreting cytokines
Plasma cells
Produce
antibodies
Helper T cell activates specific B cell by secreting cytokines
Antibodies bind to antigen
yellow) (
Antigen -
antibody complex
engulfed & destroyed by
phagocytes
Activated B cell divides & differentiates
Memory B Cells
-held in reserve
-Activated with 2nd exposure to antigen

36. ANTIBODY STRUCTURE Structure
Antigen binding site
Antigen binding site
Structure
-2 parallel polypeptide chains 2 heavy chains (red)
-2 light chains (blue)
-Each chain has constant segment (solid) variable segment (dashed)
-Variable segment varies depending on targeted antigen
Action
-Do not target the antigen
-Targets portion of antigen called antigenic determinant site
-Complete antigen must have 2 antigenic determinant sites – one for each arm of antibody