Chapter 12
The Lymphatic and
Body Defenses
• General
– subsystem of circulatory system
– functions
• fight disease
• clean blood
• fluid balance
– a drainage system
• 3 liters liquid out of blood per day
blood capillaries reabsorb 85%
• 15% (2 – 4 L/day) of the water and about
half of the plasma proteins enters
lymphatic system and then returned to
the blood
Lymphatic and Immune Systems
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Capillary bed
Tissue fluid
Tissue cell
Lymphatic
capillary
Venule
Arteriole
Figure 21.3a
(a)
• maintain fluid balance
• protect body from infection
and disease
21-4
• Circulation
– lymph fluid
• interstitial fluid “clear ”
– lymph capillaries
• take fluid out of
capillary beds by
diffusion
– lymph vessels
“lymphatics”
• carry fluid
through the body
– lymph nodes- axillary cervical
inguinal - about 450 in young adult
• remove foreign substances
• macrophages, lymphocytes, monocytes
• nodes inflamed tender “bubo”
Lymphatic ducts
• right lymphatic duct- drains the right arm,
shoulder area, and the right side of the head
and neck.
• thoracic duct-drains everything else,
including the legs, GI tract and other
abdominal organs, thoracic organs, and the
left side of the head and neck and left arm
and shoulder.
• lymph ---> into blood via subclavian veins
Lymphatic Drainage of
Mammary and Axillary Regions
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Right lymphatic duct
Right subclavian
vein
Axillary lymph
nodes
Lymphatics
of breast
(b)
21-9
Figure
21.6b
The Fluid Cycle
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Lymphatic system
Cardiovascular system
Cervical lymph nodes
Lymphatic
capillaries
Pulmonary
circuit
Lymph
nodes
Palatine tonsil
L. internal jugular v.
Thoracic duct
R. lymphatic duct
Thymus
Lymphatic
trunks
Collecting
duct
Axillary lymph node
Subclavian vein
Thoracic duct
Cisterna chyli
Spleen
R. and l. lumbar trunks
Abdominal,
intestinal,
and mesenteric
lymph nodes
Superior
vena cava
Collecting
vessels
Intestinal trunk
Red bone marrow
Inguinal lymph nodes
Blood
flow
Popliteal lymph nodes
Lymph
flow
Systemic
circuit
Lymphatic vessels
Lymphatic
capillaries
Figure 21.5
21-10
Figure 21.1
• Other Lymphatic Organs
– spleen
• make lymphocytes
• filter out debris and deadly pathogens
– thymus gland
• T cells, more immunocompetent
– Peyer’s Patches
• end of ileum
– MALT mucosa associated lymphatic tissue
• tonsils, Peyers patches, and appendix
– tonsils
• rings of lymphatic tissues that trap
pathogens crypts
– palatine tonsils
• pair at posterior margin of oral cavity
• most often infected
– lingual tonsils
• pair at root of tongue
– pharyngeal tonsil (adenoid)
• single tonsil on wall of nasopharynx
• Tonsillectomy removal of palatine &
linguinal
Defenses Against Pathogens
• pathogens – environmental agents capable of
producing disease
– infectious organisms, toxic chemicals, and radiation
• three lines of defenses against pathogens:
– first line of defense – external barriers, skin and mucous
membranes
– second line of defense – several nonspecific defense
mechanisms
• leukocytes and macrophages, antimicrobial proteins, immune
surveillance, inflammation, and fever
• effective against a broad range of pathogens
– third line of defense – the immune system
• defeats a pathogen, and leaves the body of a ‘memory’ of it so it can
defeat it faster in the future
21-15
Non - Specific Body Defense
• Surface membranes
– skin
• many layers - closely packed cells
• pH 5.5
– epithelial & mucous membranes
• saliva & tears : lysozyme
• cilia - move foreign substances to
esophagus
• stomach - gastric juice - HCl pH 1-2
• mucus - trap pathogens & dirt
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Mobilization of Defenses
• leukocyte behavior
Splinter
– margination
From
damaged
tissue
• selectins cause
leukocytes to adhere
to blood vessel walls
1
Inflammatory
chemicals
Bacteria
From
mast
cells
From
blood
Mast cells
• leukocytes squeeze
between endothelial
cells into tissue
space
4
Chemotaxis
Increased
permeability
3
Neutrophils
– diapedesis
(emigration)
5
Phagocytosis
2
Margination
Blood capillary
or venule
Diapedesis
21-17
Figure 21.19
• White Blood Cells- Leukocytes
– defense and immunity 5000 - 10,000 WBC’s
• neutrophil’s ~ 3,000 - 7,000 54-62% of WBC
–Phagocytes
–Chemical killing zone(superoxide, H2O2,
hypochlorite)
• eosinophils ~ 100-400 1-3% of WBC
–Chemicals (superoxide, H2O2, toxins)
– kill parasitic worms allergies
• basophils ~ 20-30 less than 1% of WBC
–secrete histamines - vasodilators
–chemicals to kill foreign substances
–heparin
• Monocytes 100-700 3-9 % of WBC
– Large cells
– Macrophages- go into connective
tissue
– Present in chronic infections
• Lymphocytes ~ 1500 – 3000 25-33%
– small cells - r.b.c size
– Provide immunity B cells, T cells,
and natural killer cells
– Secrete antibodies
Macrophages
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Macrophages
Pseudopods
Bacteria
Peter Arnold, Inc.
21-20
Figure 21.7
5 µm
– inflammation
• secondary line of defense
• heat red swelling and pain
• seal off area / more blood
• histamines and kinins inflammatory chemicals also
attract neutrophils
• pus : dead neutrophil’s & dead
pathogens
• absceses
• Antimicrobial Chemicals
– complement
• 20 plasma proteins attach to foreign cells
– interferon
• proteins released from virus infected
cells which protects other cells from
virus
– fever
• w.b.c secrete pyrogens
• raise body temp. inhibits bacterial growth
• Decreases iron in blood- inhibits growth
of bacteria and fungi
• Increases phagocytic action
Specific Defense Mechanisms
• General
– types
• cellular ~ lymphocytes T cells
• humoral ~ antibodies B cells
– immune response
• antigen specific
• systemic
• memory
• Antigens
– proteins which cause an immune response
• Cells of the Immune System
– lymphocytes
• T cells - cell mediated
• B cells - make antibodies humoral
– macrophages
•
•
•
•
engulf foreign particles – monocytes neutrophils
T cells - release chemicals create macrophages
T’ stand for thymus derived
have best ability to recognize foreign antigens
– B cells
• bind to antigens
• T helper cells release chemical so B cells make clones
• plasma cells secrete antibodies
• B cells can become memory cells
remember foreign antigens
• Active Immunity
– have or exposed to disease
– naturally acquired - had disease
– artificially “ - vaccine
– vaccines - dead, weakened pathogen
• Passive Immunity
– antibodies transferred
– naturally acquired - placenta “mother’s
milk” IgG’s
– artificial “ – gamma globulins
• Antivenoms
tetanus
botulism
• Antibodies
– Structure –
– Classes of Antibodies
• IgM - 1st released B cells
• IgA - in tears saliva mucus
• IgD - activate B cells
• IgG - most abundant -- >
placenta
• IgE - skin gastrointestinal
respiratory tracts release
histamine
– Antibody function
• complement system - antibodies
bind to antigen lyse foreign
cells
• neutralization - antibodies bind
to specific sites or neutralize
foreign substances
• agglutination - antibodies bind
to antigens --> clumping effect
• precipitation - antibodies and
antigens form precipitate
insoluble substances
Cell Mediated Immunity
• T Cells
– killer T cells - secret chemical --> kill
virus infested cells – helper T cells - stimulate production
of killer T and B cells
– suppresor T Cells - slows killer and B
cells
• Memory Cells
– B plasma cells- secrete antibodies
Organ Transplant and Rejection
• Grafts - 75 % match
– autografts
• same person site to site
– isografts
• twin identical
– allografts
• unrelated persons
– xenografts
• different species
Disorders of Immunity
• Allergies
– abnormal immune response
– immediate hypersensitivity
• inflammatory response
• runny nose, watery eyes, itching, redness
• basophiles IgE --> histamines
• acute systemic- anaphylatic shock
– delayed hypersensitivity
• reaction 1-3 days
• T cells release lympokines
• poison ivy
• Immunodeficiencies
– SCID - lack of B and T cells
vulnerability to opportunistic
infection and must live in protective enclosures
– AIDS - destroy helper T cells
• incubation period from several months to 12 years
• Autoimmune Disease
– against its own tissue
– some resulting disease
• multiple sclerosis
• myasthenia gravis
• graves disease
• systemic lupus
• rheumatoid arthritis
• Hashimotos thyroditis
– causes
• virus or infection alters your self protection
Developmental Aspects
• Immunity
– genetics
– stress
– depression
– mind over matter
– diet