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 dayblood 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

• maintain fluid balance• protect body from infection and disease21-4

Figure 21.3a

(a)

Arteriole

Capillary bed

Tissue fluid

Tissue cell

Lymphaticcapillary

Venule

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• 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

21-9Figure 21.6b(b)

Right lymphatic duct

Right subclavianvein

Axillary lymphnodes

Lymphaticsof breast

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The Fluid Cycle

21-10Figure 21.1Figure 21.5

Subclavian vein

Cardiovascular systemLymphatic system

Lymphaticcapillaries

Lymphnodes

LymphatictrunksCollectingduct

Collectingvessels

Lymphflow

Lymphaticcapillaries

Pulmonarycircuit

Superior vena cava

Bloodflow

Systemiccircuit

Axillary lymph node

Spleen

Inguinal lymph nodes

Cervical lymph nodes

R. lymphatic duct

Thymus

Thoracic duct

Cisterna chyli

Palatine tonsil

Red bone marrow

Thoracic duct

Intestinal trunk

R. and l. lumbar trunks

Popliteal lymph nodes

Abdominal,intestinal,and mesentericlymph nodes

Lymphatic vessels

L. internal jugular v.

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• 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 future21-15

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

Mobilization of Defenses

• leukocyte behavior– margination

• selectins cause leukocytes to adhere to blood vessel walls

– diapedesis (emigration)

• leukocytes squeeze between endothelial cells into tissue space

21-17Figure 21.19

Splinter

Phagocytosis

1

5

Chemotaxis4

2

Mast cells

Margination

Diapedesis3

Neutrophils

Bacteria

Fromdamaged

tissue

Inflammatorychemicals

Frommastcells

Fromblood

Increasedpermeability

Blood capillaryor venule

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• 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

21-20Figure 21.7

5 µm

Macrophages

Pseudopods

Bacteria

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Peter Arnold, Inc.

– 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