Transcript The Lymphatic and Immune Systems

CHAPTER
28
The Lymphatic and
Immune Systems
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
28-2
Learning Outcomes
28.1
List the pathways and organs of the lymphatic
system and give their locations.
28.2
Define lymph and tell how it is circulated in the body.
28.3
Define the terms infection, pathogen, and antigen.
28.4
List and describe the nonspecific body defense
mechanisms.
28.5
Explain the signs and causes of inflammation.
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28-3
Learning Outcomes (cont.)
28.6
Explain what is meant by body defenses.
28.7
Define B cells and T cells and describe their
locations and functions.
28.8
Explain the importance of MHC proteins.
28.9
List the different types of T cells and describe their
functions.
28.10 Explain how antibodies fight infection.
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28-4
Learning Outcomes (cont.)
28.11 List the different types of antibodies and tell how
they differ.
28.12 Define complement proteins and give their function.
28.13 Explain the difference between the primary immune
response and secondary immune response.
28.14 Explain the four different types of acquired
immunities.
28.15 Describe the function of a vaccine.
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28-5
Learning Outcomes (cont.)
28.16 Define the terms cancer and carcinogen.
28.17 Describe how cancers are diagnosed and treated.
28.18 Explain how cancers are classified.
28.19 Describe how allergies develop.
28.20 Describe the causes, signs and symptoms, and
treatments of other common immune disorders.
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28-6
Introduction
• Immune system
– Protects the body
against
•
•
•
•
•
•
Bacteria
Viruses
Fungi
Toxins
Parasites
Cancer
• Lymphatic system
– Works with immune
system to remove
disease-causing
agents
– Organs
• Thymus
• Spleen
• Lymph nodes
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28-7
The Lymphatic System
• Network of
connecting vessels
– Collects fluid (lymph)
between cells and
returns it to
bloodstream
– Picks up lipids from
digestive organs and
transports them to
bloodstream
– Functions to defend
the body against
pathogens
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28-8
Lymphatic Pathways
• Lymphatic capillaries
– Extend into interstitial spaces
– Permeable, thin walls pick up fluid, now lymph
– Delivers lymph to lymphatic vessels
• Lymphatic vessels
– Deliver lymph to lymph nodes
• Cells in nodes can remove pathogens from lymph
and start an immune response
– Leaves nodes through efferent lymphatic
vessels
Lymph
System
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Lymphatic Pathways (cont.)
• Lymphatic trunks
– Receive lymph from efferent lymphatic
vessels
– Deliver it to
• Lymphatic collecting ducts
– Thoracic duct
• Left side of head and neck, left arm, left side of
thorax, entire abdominopelvic area, and both legs
Lymph
System
– Right lymphatic duct
• Right side of head and neck, right arm, and right
side of chest
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28-10
Tissue Fluid and Lymph
• Interstitial fluid
– Fluid in spaces between cells that has leaked
from blood capillaries and has not been
picked up by body cells
– High in nutrients, oxygen, and small proteins
– Becomes lymph
• Pushed through lymphatic vessels by squeezing
action of neighboring skeletal muscles and
breathing movement
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28-11
Back
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28-12
Lymph Nodes
• Small, glandular
structures
• Located along paths
of larger lymphatic
vessels
– Afferent lymphatic
vessels – Lymph to
node
– Efferent lymphatic
vessels – Lymph from
node
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28-13
Lymph Nodes (cont.)
• More lymph enters
than can leave at one
time
• Cells in nodes
– Macrophages – digest
unwanted pathogens
– Lymphocytes – start
an immune response
against pathogen
• Nodes can generate
some lymphocytes
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28-14
The Thymus and Spleen
• Thymus
– Soft, bi-lobed organ
– Located just above the heart in the mediastinum
– Large in children, shrinks as we age
– Functions
• Same as lymph nodes
• Also produces lymphocytes
• Produces thymosin – stimulates production of lymphocytes
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28-15
The Thymus and Spleen (cont.)
• Spleen
– Largest lymphatic organ
– Located in the upper left quadrant of
abdominal cavity
– Functions
• Filters blood similarly to lymph nodes
• Removes worn-out red cells
– If removed (splenectomy), liver takes over
most of its function
© 2011 The McGraw-Hill Companies, Inc. All rights reserved.
28-16
Apply Your Knowledge
What are the lymphatic collecting ducts and
what area do they drain?
ANSWER: The collecting ducts are:
Thoracic duct, which drains the left side of the head
and neck, left arm, left side of thorax, entire
abdominopelvic area, and both legs; and the right
lymphatic duct, which drains the right side of the head
and neck, right arm, and right side of the chest.
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28-17
Defenses Against Disease
• Infection
– The presence of a
pathogen in or on the
body
• Pathogen
– A disease-causing
agent
• Innate immunity
– Nonspecific defenses
to protect against
pathogens
• Nonspecific defenses
– Species resistance
– Mechanical barriers
– Chemical barriers
– Phagocytosis
– Fever
– Inflammation
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28-18
Specific Defenses Against Disease
• Immunities
– Protect against very
specific pathogens
– Antigens
• Foreign substances in
the body
– Haptens
• Foreign substances too
small to start an
immune response by
themselves
• Other substances
– Proteins – antibodies
and complements
– WBCs – lymphocytes
and macrophages
– Lymph system
• Cytokines – assist in
immune response
regulation
• Monokines – increase
B cell production and
stimulate WBC
production
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Defenses Against Disease (cont.)
Two major types of lymphocytes
Diagram
B Cells and T Cells
Recognize antigens in the body
B cells
Respond to antigens by
becoming plasma cells
 Plasma cells make antibodies
 Memory B cells produce
stronger response with next
exposure to antigen

T Cells
Cell-mediated response
 Bind to antigens on cells
and attack them directly
 Secrete lymphokines that
increase T cell production and
directly kill cells with antigens

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Defenses Against Disease (cont.)
• T cell activation
– Begins when macrophage ingests and digests
pathogen with antigen on it
– Antigens are placed on cell membrane of
macrophage
– T cell recognizes and binds to antigen and the
major histocompatibility complex (MHC) on
the surface of the macrophage
– Now can divide to form other types of T cells
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28-22
Defenses Against Disease (cont.)
• Types
– Cytotoxic T cells
• Protect body against viruses and cancer cells
– Helper T cells
• Increase antibody formation, memory cell
formation, B cell formation, and phagocytosis
– Memory T cells
• Remember the pathogen that activated original
T cell
• Later exposures trigger an immune response more
effective than initial response
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28-23
Defenses Against Disease (cont.)
• Natural killer (NK)
cells
– Type of lymphocyte
– Primarily target cancer
cells
– Kill on contact
– Do not recognize a
specific antigen
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28-24
Apply Your Knowledge
Identify whether each item refers to T cells, B cells, or NK
cells:
ANSWER:
NK Primarily target cancer cells
___
B Respond to antigens by becoming plasma cells
___
T Must be activated to respond to an antigen
___
T Bind to antigens on cells and attack them directly
___
NK Kill on contact
___
T Need macrophages and MHC for activation
___
B Make antibodies against specific antigen
___
Right on
Target!
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28-25
Antibodies
• Also called immunoglobulins
– IgA
• Prevents pathogens from entering body
– IgD
• Found on B cell membranes
• Thought to control B cell activity
– IgE
• Found with IgA
• Involved in triggering allergic reactions
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Antibodies (cont.)
– IgG
• Recognizes bacteria, viruses, and toxins
• Activates complements
– IgM
• Large and binds to antigens on food,
bacteria, or incompatible blood cells
• Activates compliments
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28-27
Antibodies (cont.)
• Actions that occur when antibodies bind to
antigens
– Allow phagocytes to recognize and destroy antigens
– Cause antigens to clump together, causing them to
be destroyed by macrophages
– Cover the toxic portions of antigens, making them
harmless
– Activate complement
• Group of proteins in serum that attack pathogens by forming
holes in them
• Attract macrophages to pathogens and can stimulate
inflammation
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28-28
Apply Your Knowledge
What are the possible actions that occur when
antibodies bind to antigens?
ANSWER: Possible actions include:
 They allow phagocytes to recognize and destroy
antigens.
 They make antigens clump together, causing them to be
destroyed by macrophages.
 They cover the toxic portions of antigens to make them
harmless.
 They activate complements.
Very Good!
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28-29
Immune Responses and Acquired Immunity
• Primary immune response occurs with first
exposure to antigen
– Slow process
– Memory cells are formed
• Secondary immune response with next
exposure to same antigen
– Quick and carried out by memory cells
– Usually prevents person from developing disease
from the antigen
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28-30
Immune Responses and Acquired Immunity
(cont.)
• Naturally acquired active immunity
– Natural exposure to antigen – having an
illness
– Makes antibodies and memory cells
– Long-lasting
• Artificially acquired active immunity
– Injected with pathogen – immunizations or
vaccines
– Makes antibodies and memory cells
– Long-lasting
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28-31
Immune Responses and Acquired Immunity
(cont.)
• Naturally acquired passive immunity
– Acquired from mother
• Breast milk
• Placenta
– Short-lived
• Artificially acquired passive immunity
– Injected with antibodies (such as antivenom)
– Short-lived
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28-32
Apply Your Knowledge
After you give an immunization to a 2-year-old,
her mother asks you why this will work to
prevent her from getting a disease.
ANSWER: Immunization is an artificially acquired
immunity because a person develops this immunity
by being injected with a pathogen and then making
antibodies and memory cells against the pathogen.
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Major Immune System Disorders
• Cancer
– Uncontrolled growth of abnormal cells form
malignant tumors
– Factors known to cause cancer are called
carcinogens
– Treatment based on stage
0 – very early; cancer cells localized
I – spread to deeper layers or some in surrounding tissues
II – spread to surrounding tissues but contained in primary site
III – spread beyond primary site into nearby areas
IV – spread to other organs
Recurrent – reappeared after treatment
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Major Immune System Disorders (cont.)
• Allergies
– Immune response to an allergen
– IgE antibodies bind to allergens and
stimulate mast cells to release histamine and
heparin, triggering allergic response
– Allergy shots
• Small amounts of allergen stimulates production of
IgG to prevent IgE from binding to antigen
• IgG antibodies do not stimulate mast cells, so
immune response is not generated
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28-35
Major Immune System Disorders (cont.)
– Allergy signs/symptoms
• Inhaled allergens – runny nose, sneezing, coughing,
wheezing
• Ingested allergens – nausea, vomiting, diarrhea
• Skin allergens – rashes
• Allergens in blood – most life-threatening; can affect many
organs
– Treatment
• Antihistamines, decongestants – OTC or prescription
• Epinephrine for anaphylaxis – vasoconstriction,
increasing BP
– Anaphylaxis – life-threatening response
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28-36
Common Immune System Disorders
• Autoimmune disease
– Body attacks its own antigens
– Examples
•
•
•
•
•
•
Scleroderma
Rheumatoid arthritis
Multiple sclerosis
Glomerulonephritis
Crohn’s disease
Diabetes mellitus, type I
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Common Immune System Disorders (cont.)
Disorder
Description
AIDS
Development of severe signs and symptoms caused
by HIV as it destroys lymphocytes; leaves immune
system weakened and susceptible to other diseases
Chronic fatigue
syndrome (CFS)
Condition of severe tiredness not relieved by rest
and not related to other illnesses
Lymphedema
Blockage of lymphatic vessels results in tissue
swelling that increases over time
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28-38
Common Immune System Disorders (cont.)
Disorder
Description
Mononucleosis
“Mono”; highly contagious viral infection spread
through saliva of infected person
Systemic lupus
erythematous
(SLE)
Autoimmune disorder; produces antibodies that
target own cells and tissues; affects women more
often than men
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Apply Your Knowledge
Matching:
ANSWER:
G Immune response to a substance
___
A. CFS
E Blockage of lymphatic vessels
___
B. SLE
___
F “Kissing disease”
C. Cancer
B “Butterfly” rash on face
___
D. Autoimmune disease
A Severe tiredness
___
E. Lymphedema
C Uncontrolled growth of abnormal cells
___
F. Mononucleosis
D Body attacks its own antigens
___
G. Allergy
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28-40
In Summary
28.1 The lymph system is composed of pathways known
as lymph vessels. In addition to the lymph vessels,
the organs of the lymphatic system include lymph
nodes located throughout the body, the thymus in the
mediastinum, and the spleen located in the LUQ.
28.2 Lymph is the body fluid found between the body’s
cells. It circulates through the body via lymphatic
capillaries, lymphatic vessels, lymph nodes, lymphatic
trunk, collecting ducts, and to the subclavian vein.
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28-41
In Summary (cont.)
28.3 Infection is the presence of a pathogen in or on the
body. A pathogen is a disease-causing agent, and
antigens are foreign substances within the body that
may or may not cause disease.
28.4 The nonspecific body defenses include species
resistance, mechanical and chemical barriers,
phagocytosis, fever, and inflammation.
28.5 Inflammation is the result of injury or infection. Signs
are redness, heat, swelling, and pain.
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28-42
In Summary (cont.)
28.6 Specific defenses are immunities or defenses against
very specific antigens.
28.7 B and T cells come from the bone marrow, thymus,
lymph nodes, spleen, and the lining of the digestive
tract and are found circulating in the blood. B cells
utilize memory and plasma cells in a process called
humoral or antibody-mediated immunity, and T cells
bind directly to cell antigens, attacking them directly,
producing cell-mediated immunity.
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28-43
In Summary (cont.)
28.8 T cells cannot be activated to produce immunity
without MHC proteins and macrophages.
28.9 Activated T cells may form cytotoxic cells which
protect the body against viruses and certain types of
cancer. Other T cells may become helper T cells,
which increase antibody and memory cell and B cell
formation and phagocytosis. Still other T cells
become memory cells.
28.10 Antibodies may work in the following ways:
phagocytosis, antigen clumping, covering
(inactivating) toxic portions of antigens, and
activating complements.
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28-44
In Summary (cont.)
28.11 Antibodies are also known as immunoglobulins. IgA
prevents pathogens from entering the body; IgD
controls B cell activity; IgE works with IgA in
triggering allergic reactions; IgG recognizes bacteria,
viruses and toxins and activates complements; and
IgM binds to antigens on food, bacteria, or
incompatible blood cells. IgM also activates
complements.
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28-45
In Summary (cont.)
28.12 Complements are serum proteins that attack
pathogens by forming holes in them. They also
attract macrophages and can stimulate inflammation.
28.13 A primary immune response occurs the first time a
person is exposed to an antigen. The response is
slow and takes several weeks to occur. A secondary
immune response occurs at the next exposure. This
response is very quick and may prevent the person
from becoming ill.
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28-46
In Summary (cont.)
28.14 The four types of immune response are natural
active immunity, such as when someone becomes ill
and develops immunity; artificial active immunity, as
when an injection is given against a pathogen,
preventing illness; natural passive immunity occurs
when an infant has its mother’s immunity for a short
while after birth and through breast-milk; and artificial
passive immunity occurs after injection of antibodies
such as with an antivenom.
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In Summary (cont.)
28.15 Vaccines are used to produce artificially acquired
active immunity.
28.16 Cancer is defined as the uncontrolled growth of
abnormal cells. A carcinogen is an agent that is
known to cause cancer.
28.17 Cancer diagnoses can come about in many ways,
but often a biopsy confirms the diagnosis.
Treatments vary depending on the type and stage of
the cancer, but treatment options include surgery,
including bone marrow transplants, chemotherapy,
and radiation therapy, as well as newer immune
therapies.
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28-48
In Summary (cont.)
28.18 Cancers are classified as Stages IIV and recurrent.
Definitions of these stages may be found in Table
28-1.
28.19 An allergic reaction is an immune response to a
substance that is not normally considered harmful to
the body. Allergic reactions can also be an
excessive immune response. Allergens are
substances that produce an allergic response.
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In Summary (cont.)
28.20 Diseases and disorders of the immune system
include autoimmune diseases, where the body
attacks its own antigens, as well as numerous other
diseases, including some cancers, caused by
pathogens, allergens, and other antigens. The signs,
symptoms and treatments are as numerous and
varied as the diseases. Some of the more common
diseases and disorders are discussed in the
Pathophysiology section at the end of this chapter.
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28-50
End of Chapter 28
Thought is an infection.
In the case of certain
thoughts, it becomes an
epidemic.
~Wallace Stevens
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