Transcript The Lymphatic System

The Lymphatic
System
Non-Specific Defenses
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Physical Barriers
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Phagocytes
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Slow spread of viral infections
Stimulate macrophages and NK cells
Inflammation
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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
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Epithelium, hair, secretions, acid, enzymes
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)
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Pyrogens – proteins reset body's “thermostat”
Incr. rate of metabolism
Over 104oF damages CNS, nausea, hallucination, and convulsions
Organization
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Lymph Vessels
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Lymph Fluid
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Cells defend body
80% last 4 years…some last 20 years or
more!
Lymph Tissue
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Blood plasma but w/less proteins
Lymphocytes
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Begin at peripheral tissue venous system
Small valves prevent backflow
Loose connective tissue
Tonsils, Appendix, Peyer’s Patches
Size can increase or decrease depending
on number of lymphocytes
Lymph Organs
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Lymph nodes
Spleen
Thymus
Lymph Vessels
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Lead towards trunk of body
and empty into 2 ducts
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Thoracic duct – lower
abdomen, pelvis, lower
limbs, left head, neck, and
chest
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Right lymphatic duct – right
side of body, above
diaphragm
Lymphodema (edema) –
blockage of lymph drain
Functions
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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
Lymphoid Organs
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Lymph Nodes
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Thymus
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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
Decrease in size after puberty
T cell production and maturation
Spleen
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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
Lymphocytes
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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
Specific Defenses
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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
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”
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Immune Response (cell
mediated)
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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
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Helper T cells
• Recruit other cells to fight invaders
• Stimulates B cells to increase production of antibodies
• Simulates Killer T cells to multiply
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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
Properties of Immunity
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Specificity
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Versatility
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Millions different lymphocytes w/diff antigen
receptors
Memory
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T cells and B cells target one specific antigen
1st exposure – lymphocytes divide to create
“attack” cells and memory cells
Response to 2o exposure to antigen is stronger
than 1st
Tolerance
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Doesn’t respond to normal “self” tissues or
antigens
Types of Immunity
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Innate – genetically determined
Acquired – arises during life
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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
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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
Lymphatic Project
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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