The Lymphatic System and Immunity
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Transcript of The Lymphatic System and Immunity
Draining excess interstitial fluid
Transporting dietary lipids
Lymphatic vessels:• In spaces between cells• Closed at one end, converge to form larger vessels (like veins) to trunks to right and left duct to venous blood• Contain valves to ensure
one way movement• Flow through lymph nodes (masses of B and T cells) Lymphatic capillaries:• Anchored by elastic filaments• Open and close with pressure differences
Figure 12.3
Regionallymph nodes:
Cervicalnodes
Axillarynodes
Inguinalnodes
KEY:
Drained by the right lymphatic ductDrained by the thoracic duct
Lymphatics
Cisterna chyli (receiveslymph drainage from digestive organs)
Spleen
AortaThoracic duct
Thoracic ductentry into leftsubclavian vein
Internal jugular vein
Entrance of rightlymphatic duct into rightsubclavian vein
Lymphatic Organs & Tissues
• Divided into 2 groups– Primary lymphatic organs
• Sites where stem cells divide & become immunocompetent
• Red bone marrow, thymus– Secondary lymphatic organs
• Sites where immune response occurs• Lymph nodes, spleen, lymphatic nodules, etc.
Thymus:• Located between sternum and
aorta (mediastinum)• Two lobes divided into lobules• Cortex (outer layer) of
immature cells -T cells: antigenic activity:
-dendritic cells: assist maturation-epithelial cells: “educate” pre-T cells by positive selection-macrophages: clear debris
and dead cells • Medulla (inner layer) of mature
T cells, epithelial cells, dendritic cells, and macrophages
Lymph nodes: • Lymph flows in through afferent vessels and out through efferent vessels• Made up of nodules
-Primary nodules: B cells
-Secondary nodules: plasma cell and memory B cell formation
Spleen: • Located between stomach and
diaphragm• Contains white and red pulp
-White pulp: lymphocytes and macrophages around central arteries
-Red pulp: red blood cells, macrophages, lymphocytes, plasma cells,
and granulocytes• Removes worn out or
defective RBCs
• Stores platelet• Produces blood cells in
fetus
Lymphatic nodules: no capsule• Throughout mucus
membranes (MALT= mucosa-associated lymphatic tissue)
• Tonsils
Figure 12.6
Nonspecific Resistance/ Innate Defenses: born with and offer immediate protection• First line of defense- skin and mucous membranes
• Physical and chemical barrier
Inflammation
Figure 12.7
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Adaptive Defense System: Third Line of Defense•Three aspects of adaptive defense•Antigen specific—recognizes and acts against particular foreign substances•Systemic—not restricted to the initial infection site•Memory—recognizes and mounts a stronger attack on previously encountered pathogens
© 2012 Pearson Education, Inc.
Adaptive Defense System: Third Line of Defense•Cells of the adaptive defense system•Lymphocytes respond to specific antigens•B lymphocytes (B cells)•T lymphocytes (T cells)
•Macrophages help lymphocytes
© 2012 Pearson Education, Inc.
Adaptive Defense System: Third Line of Defense• Immunocompetent—cell becomes capable of responding to a specific antigen by binding to it•Cells of the adaptive defense system •Lymphocytes•Originate from hemocytoblasts in the red bone marrow•B lymphocytes become immunocompetent in the bone marrow (remember B for Bone marrow)•T lymphocytes become immunocompetent in the thymus (remember T for Thymus)
Figure 12.11, step 1a
Red bone marrow: site of lymphocyte origin
Primary lymphoid organs: site ofdevelopment of immunocompetence asB or T cellsSecondary lymphoid organs: site ofantigen encounter, and activation tobecome effector and memory B or T cells
Immature (naive)lymphocytes
Redbone marrow
KEY:
Figure 12.11, step 1b
Red bone marrow: site of lymphocyte origin
Primary lymphoid organs: site ofdevelopment of immunocompetence asB or T cellsSecondary lymphoid organs: site ofantigen encounter, and activation tobecome effector and memory B or T cells
Lymphocytes destined to become T cellsmigrate (in blood) to the thymus and develop immunocompetence there. B cells develop immunocompetence in red bone marrow.
Bone marrowThymus
Immature (naive)lymphocytes
Redbone marrow
1
KEY:
Figure 12.11, step 2
Red bone marrow: site of lymphocyte origin
Primary lymphoid organs: site ofdevelopment of immunocompetence asB or T cellsSecondary lymphoid organs: site ofantigen encounter, and activation tobecome effector and memory B or T cells
Lymphocytes destined to become T cellsmigrate (in blood) to the thymus and develop immunocompetence there. B cells develop immunocompetence in red bone marrow.
Immunocompetent but still naive lymphocytes leave the thymus and bone marrow. They “seed” the lymph nodes, spleen, and other lymphoid tissues, where they encounter their antigen and become activated.
Lymph nodes,spleen, and otherlymphoid tissues
Bone marrowThymus
Immature (naive)lymphocytes
Redbone marrow
1
2
KEY:
Figure 12.11, step 3
Red bone marrow: site of lymphocyte origin
Primary lymphoid organs: site ofdevelopment of immunocompetence asB or T cellsSecondary lymphoid organs: site ofantigen encounter, and activation tobecome effector and memory B or T cells
Lymphocytes destined to become T cellsmigrate (in blood) to the thymus and develop immunocompetence there. B cells develop immunocompetence in red bone marrow.
Immunocompetent but still naive lymphocytes leave the thymus and bone marrow. They “seed” the lymph nodes, spleen, and other lymphoid tissues, where they encounter their antigen and become activated.
Antigen-activated (mature) immunocompetent lymphocytes (effector cells and memory cells) circulate continuously in the bloodstream and lymph and throughout the lymphoid organs of the body.
Lymph nodes,spleen, and otherlymphoid tissues
Bone marrowThymus
Immature (naive)lymphocytes
Redbone marrow
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2
3
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A recent trial in mice has just shown that a certain antibody successfully shrank tumors in breast, brain, prostate, and colon cancer, among many others. The drug works by blocking the protein CD47, which tells the immune system not to attack the cell. This protein is found in regular cells, but is much more abundant in cancer cells. A $20 million grant has just been awarded, allowing researchers to begin the first phases of human trials.
Active immunity