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Copyright 2009, John Wiley & Sons, Inc.
Chapter 22: The Lymphatic
System and Immunity
Videos
Crash course Immunity:
https://youtu.be/CeVtPDjJBPU
Crash course Lymphatic system:
https://youtu.be/I7orwMgTQ5I
Copyright 2009, John Wiley & Sons, Inc.
Copyright 2009, John Wiley & Sons, Inc.
Immunity or Resistance
2 types of immunity
Innate or nonspecific immunity – present at birth
No specific recognition of invaders (attacks anything that is foreign)
No memory component
1st line of defense
Adaptive or specific immunity
Specific recognition of invaders
Memory component
Copyright 2009, John Wiley & Sons, Inc.
Lymphatic system structure and function
Lymphatic system - Consists of
lymph, lymphatic vessels, and
lymphatic tissue.
Functions of the lymphatic system
1. Drain fluids
2. Transport lipids
3. Immune responses
Copyright 2009, John Wiley & Sons, Inc.
Lymphatic system structure and function
Lymphatic vessels Resemble veins
in structure.
Lymph nodes – sections of
lymphatic tissue that contains B and
T cells.
Copyright 2009, John Wiley & Sons, Inc.
Lymphatic system structure and function
2 main channels for
lymphatic fluids –
Thoracic duct
Right lymphatic duct
Copyright 2009, John Wiley & Sons, Inc.
Lymphatic tissues and organs
Primary lymphatic organs
Red bone marrow and thymus
where stem cells divide and
become immune cells
Secondary lymphatic organs
Lymph nodes, spleen,
lymphatic nodules
where immune response
occurs
Copyright 2009, John Wiley & Sons, Inc.
Thymus and Medulla
Thymus
Immature T cells migrate here from red bone marrow.
Eventually mature.
Macrophages clear out dead and dying cells
Thymus shrinks with age from 70g in infants to 3g in old age
Lymph nodes
Located along lymphatic vessels
Scattered throughout body
Outer cortex – B cells mature.
Inner cortex – mainly T cells and dendritic cells
Medulla – B cells and macrophages
Copyright 2009, John Wiley & Sons, Inc.
Lymph
Lymph flows through a node in 1 direction only
Enters through afferent lymphatic vessels
Brings lymph, antibodies and T cells out of the efferent lymphatic vessels to the rest of the body.
Lymph nodes function as a filter
Foreign substances trapped
Destroyed by macrophages or immune response
Copyright 2009, John Wiley & Sons, Inc.
Spleen
Largest lymphatic tissue
White pulp – lymphocytes and macrophages B cells and T cells carry out
immune function
Red pulp –RBC’s, macrophages, lymphocytes, plasma cells, and granulocytes
Macrophages remove ruptured,
worn out or defective blood cells
Copyright 2009, John Wiley & Sons, Inc.
Structure of the Spleen
Immune Cells
Innate or nonspecific immunity –
Macrophages – phagocytosis and antigen presentation cell (APC)
Dendritic cells – antigen presentation cell
Neutrophils – phagocytosis
Eosinophils – parasite killers
Basophils – stimulate inflammation
Natural Killer cells – attack virus’ and tumor cells
Copyright 2009, John Wiley & Sons, Inc.
Immune Cells
Adaptive or specific immunity –
T cells – attack virus’, tumor cells,
help B cells secrete antibodies,
and secrete cytotoxins.
Includes: Helper T cells, Cytotoxic T
cells, and
B cells – turn into plasma cells,
which will secrete antibodies.
Also antigen presenting cells.
Copyright 2009, John Wiley & Sons, Inc.
Copyright 2009, John Wiley & Sons, Inc.
Innate immunity
First line of defenses: Skin and mucous membranes
Provide both physical and chemical barriers
Fluids – tears, saliva, sweat, nasal fluids.
Copyright 2009, John Wiley & Sons, Inc.
Innate immunity
Phagocytes - Neutrophils and macrophages (form from monocytes)
Natural Killer (NK) cells -Lymphocyte with the ability to kill wide variety of infected body cells and certain tumor cells Pus – pocket of dead phagocytes
and damaged tissue
Copyright 2009, John Wiley & Sons, Inc.
Inflammation
Nonspecific response of
body to tissue damage
4 signs and symptoms –
redness, pain, heat and
swelling
Attempt to dispose of microbes,
prevent spread, and prepare
site for tissue repair
Copyright 2009, John Wiley & Sons, Inc.
Adaptive immunity
Ability of the body to defend
itself against specific
pathogens.
Antigens – substances
recognized as foreign and
provoking an immune
response
Distinguished from innate
immunity by memory.
Copyright 2009, John Wiley & Sons, Inc.
Adaptive immunity
T cells and B cells - Both
develop from pluripotent
stem cells originating in red
bone marrow
B cells complete their
development in red bone
marrow (thus called B cells).
T cells migrate from red bone
marrow to mature at the
thymus (thus called T cells).
Copyright 2009, John Wiley & Sons, Inc.
Adaptive immunity
Immunocompetence – ability
to carry out adaptive immune
response
Have antigen receptors to
identify specific antigens.
Copyright 2009, John Wiley & Sons, Inc.
2 types of adaptive immunity
Cell-mediated - T cells attack
invading antigens
Effective against pathogens,
cancer cells and foreign
tissue (like transplants).
Antibody mediated - B cells
transform into plasma cells and
make antibodies (aka
immunoglobulins).
Targets pathogens in fluids
that are outside of cells.
Copyright 2009, John Wiley & Sons, Inc.
Antigens
Antigens - a foreign substance that induces an immune response in the body.
Immunogenicity – ability to provoke immune response
Reactivity – ability of antigen to react with antibodies
Entire microbes may act as antigen
Typically, just certain small parts of large antigen molecules cause a response.
Copyright 2009, John Wiley & Sons, Inc.
Antigens
B cells recognize and bind to
antigens.
T cells must be presented with
processed antigens.
Antibodies (Ab)
Antibodies - protein produced by
plasma cells that is used to
neutralize pathogens.
Can combine with the antigen that
triggered its production.
Antibodies = immunoglobulins
Neutralize antigen
Immobilize bacteria
Enhance phagocytosis
Activate T cells
Copyright 2009, John Wiley & Sons, Inc.
Copyright 2009, John Wiley & Sons, Inc.
Chemical structure of the immunoglobin (IgG) class of
antibody
Copyright 2009, John Wiley & Sons, Inc.
Copyright 2009, John Wiley & Sons, Inc.
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