1. The Lymphatic System

2. Non-Specific Defenses
Physical Barriers
Epithelium, hair, secretions, acid, enzymes
Phagocytes
1st line of cellular defense – removes debris and pathogens
Microphages leave blood stream and enter peripheral tissues (neutrophils and eosinophils)
Macrophages – sensitive to chems in surrounding fluids can be free or fixed
Interferons
Slow spread of viral infections
Stimulate macrophages and NK cells
Inflammation
Initiated by mast cells releasing histamines and heparin
Local swelling, heat, redness, and pain
Slows spread of pathogens
Necrosis – tissue destruction via lysosomes
Pus – accumulation of dead cells and debris (abscess – accumulation of pus)
Fever (>98oF)
Pyrogens – proteins reset body's “thermostat”
Incr. rate of metabolism
Over 104oF damages CNS, nausea, hallucination, and convulsions

3. Organization Lymph Vessels Lymph Fluid Lymphocytes Lymph Tissue
Begin at peripheral tissue venous system
Small valves prevent backflow
Lymph Fluid
Blood plasma but w/less proteins
Lymphocytes
Cells defend body
80% last 4 years…some last 20 years or more!
Lymph Tissue
Loose connective tissue
Tonsils, Appendix, Peyer’s Patches
Size can increase or decrease depending on number of lymphocytes
Lymph Organs
Lymph nodes
Spleen
Thymus

4. Lymph Vessels Lead towards trunk of body and empty into 2 ducts
Thoracic duct – lower abdomen, pelvis, lower limbs, left head, neck, and chest
Right lymphatic duct – right side of body, above diaphragm
Lymphodema (edema) – blockage of lymph drain

5. Functions Protect body from pathogens
Production, maintenance, and distribution of lymphocytes
Return fluid from peripheral tissues to blood
Distribute hormones, nutrients, and waste to general circulation

6. Lymphoid Organs Lymph Nodes Thymus Spleen
Filter and purify lymph before enters venous system
Detects and removes antigens
Stimulates T cells and B cells initiating immune response
Lymphomas – cancer arising from lymphocytes
Thymus
Decrease in size after puberty
T cell production and maturation
Spleen
5” long on left side, deep red
Filters blood, removes abnormal blood cells and initiates B cell and T cell responses to antigens
Macrophages identify and engulf damaged or infected cells

7. Lymphocytes 25% of circulating wbc
T cells – thymus dependent (80% circulating lymphocytes)
Cytotoxic T cells – attack foreign cells or body cells infected w/ virus
Helper T cells – stimulate T cells and B cells
Suppressor T cells – inhibit T cells and B cells
B cells -bone marrow derived (10-15% circ. Lymphocytes)
Plasma cells – secrete antibodies (immunoglobulins)
Antibodies bind to antigens
NK cells natural killer cells (5-10% circulating lymphocytes)
Attack foreign cells, viral infected cells, and cancer cells

8. Specific Defenses
Immunity – respond to the presence of specific antigens
Antigens – “non-self” substance that excites the immune system and stimulates a response
Genes determine specificity
T cells – cell mediated immunity
Defend against abnormal cells
Pathogens inside of cells
B cells – antibody-mediated immunity
Defend against antigens and pathogens in body fluids
Antibodies (immunoglobulins) – bind to specific antigen, Y shape with 2 antigen binding sites

9. Immune Response (antibody mediated)
B cell binds w/antigen…becomes activated and produces clones
B cell clones
Plasma cells – secrete antibodies (2,000 per sec!)… reaches peak 10 days
Memory B cells – continue to circulate, and can speed process to 2-3 days if recognizes an “old enemy”

10. Immune Response (cell mediated)
T cells cannot bind to “free” antigen
Macrophages and B cells must present antigen to T cells
Once T cell binds to “presented” antigen
Killer (cytotoxic) T cells
Binds to target cell and inserts a toxic chem… target cell ruptures
Helper T cells
Recruit other cells to fight invaders
Stimulates B cells to increase production of antibodies
Simulates Killer T cells to multiply
Suppressor T cells
Release chems to suppress B and T cell activity
Most T cells enlisted to fight die w/in a few days
Some remain as memory cells to respond quickly to subsequent invasions

11. Properties of Immunity
Specificity
T cells and B cells target one specific antigen
Versatility
Millions different lymphocytes w/diff antigen receptors
Memory
1st exposure – lymphocytes divide to create “attack” cells and memory cells
Response to 2o exposure to antigen is stronger than 1st
Tolerance
Doesn’t respond to normal “self” tissues or antigens

12. Types of Immunity Innate – genetically determined
Acquired – arises during life
Active – appears after exposure to antigen
Naturally- continually induced as encounter “new” pathogens or antigens
Induced – stimulated under controlled conditions
Vaccine: dead/inactive pathogen that induces an immune response
Passive – transfer of antibodies from another source
Naturally – mother to baby
Gestation – via placenta
Infancy – via breast milk
Induced – antibodies administered to fight infection or prevent disease after exposure

13. Lymphatic Project
Cartoon/comic strip analogous to lymphatic system that highlights functions of B cells, plasma cells, antibodies, and memory B cells, Helper Tcells, Killer T cells, and suppressor T cells
Research and write an essay on allergies, organ transplant and rejection, multiple sclerosis, systemic lupus, OR HIV/AIDS