Transcript Immune System

Immune System
Madeleine Myers RN, MS, FNP
Objectives
• List three functions of the lymphatic system.
• Describe the composition and flow of lymph.
• State the location of the following lymph
nodes: cervical nodes, axillary nodes, and inguinal
nodes.
• Describe the four lymphoid organs: lymph nodes,
tonsils, thymus gland, and spleen
The Lymphatic System
• Main functions:
– Return tissue fluid to the blood
– Intestinal absorption of fats and fat-soluble
vitamins
– Helps the body defend itself against disease
Functions of the Immune System
• To protect the entire body from a variety of
harmful substances
–
–
–
–
pathogenic microorganisms
allergens
toxins
malignant cells
The Lymphatic System
Elephantiasis
Plasma
• plasma
– 92% water
– 8% plasma proteins
• albumin
• globulin
• fibrinogen
• serum - plasma without clotting proteins or fibrinogen
The Lymphatic System (cont’d.)
• Lymph: clear fluid that resembles plasma
and is formed from plasma during capillary
exchange
• Composition of lymph: water, electrolytes,
waste from metabolizing cells, and some
protein that leaks out of the capillaries of
the systemic circulation
Structures of the Immune System
• Unlike other body systems, Immune System
is NOT contained within a single set of
organs or vessels
• Action depends on structures from
lymphatic, cardiovascular, and
Integumentary systems
• Works primarily through antigen-antibody
reaction
Lymphatic System
• Major structures
–
–
–
–
lymph vessels
lymph nodes
lymph fluid
tonsils
• Also
– spleen
– thymus
The Lymphatic System
Lymph System
• Lymph originates in blood
plasma
• Interstitial fluid
• cleans and nourishes body
tissues
• collects cellular debris,
bacteria
• return to blood or lymph
capillaries
Lymph Nodes
• located in lymph vessels
• small round or oval
structures (filters)
• depositories for cellular
debris
• bacteria and debris
phagocytized
Lymph Nodes
• inside are masses of tissue which contain
WBCs (lymphocytes)
• almost always grouped 2 or 3 to 100
• invading cells destroyed in nodes and often
swell as an indicator of the disease process
Spleen
• sac-like mass of
lymphatic tissue
• filter for lymph
• phagocytic cells
• hemolytic
Thymus
• lymphatic tissue
• mediastinum
• primary role: changes
lymphocytes to T cells for
cellular immunity
Tonsils
• masses of lymph tissue designed to filter tissue
fluid, not lymph
• located beneath certain areas of moist epithelium
exposed to outside and hence to contamination
• any or all may become so loaded with bacteria that
the pathogens gain dominance
• should not be removed unless absolutely necessary.
Antigen-Antibody Reactions
• Antigen - any substance that the body regards as
foreign (virus, bacterium, toxin)
• Antibody - a disease fighting protein developed by
the body in response to the presence of an antigen
• Antigen-antibody reaction or immune reaction
Web pages
• Inflamatory response
• http://www.sumanasinc.com/webcontent/animations/c
ontent/inflammatory.html
• HIV
• http://www.sumanasinc.com/webcontent/animations/content/lif
ecyclehiv.html
•
•
•
•
aninmations
http://outreach.mcb.harvard.edu/animations_S04.htm
Movie
http://www.rockefeller.edu/interactive/movies/dcell.ht
ml
Rewiew
Functions of the Lymph System
• lymph/o
• drain fluid from tissue spaces and return to
it to the blood
• transport materials (nutrients, hormones and
oxygen) to body cells
• carry away waste products to the blood
• transport lipids away from digestive system
• control of infection
Lymphoid Organs
The Lymphatic System
Lymph capillaries and blood capillaries.
The Lymphatic System (cont’d.)
• Lymphatic vessels:
includes lymphatic
capillaries and
several larger
lymphatic vessels;
“run with” the veins
Lymphoid Organs
• Organs:
–
–
–
–
Lymph nodes
Tonsils
Thymus gland
Spleen
• Functions:
– Filter particles from lymph, tissue fluid, and blood
– Support activities of lymphocytes
Immune System
Lesson 21.1 Objectives
• Differentiate between specific and nonspecific
immunity.
• Describe the process of phagocytosis.
• Explain the causes of the signs of inflammation.
• Explain the role of fever in fighting infection.
• Explain the role of T cells in cell-mediated
immunity.
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Lesson 21.1 Objectives (cont’d.)
• Explain the role of B cells in antibodymediated immunity.
• Differentiate between genetic immunity and
acquired immunity.
• Describe naturally and artificially acquired
active and passive immunity.
• Identify the steps in the development of
anaphylaxis.
Classification of the
Immune System
• Immunology: study of the immune system
• Immunity: elaborate defense system of the
human body
– Nonspecific immunity: protects the body
against many different types of foreign agents
– Specific immunity: hones in on a foreign
substance and provides protection against one
specific substance but no others
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Elsevier Inc.
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Classification of the
Immune System (cont’d.)
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29
Classification of the Immune
System (cont’d.)
• Nonspecific immunity:
– First line of defense
– Second line of defense
• Specific immunity:
– Third line of defense
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Nonspecific Immunity
• First line of defense:
– Mechanical barriers
– Chemical barriers
– Certain reflexes
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Nonspecific Immunity (cont’d.)
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Nonspecific Immunity (cont’d.)
• Second line of defense
–
–
–
–
–
Phagocytosis
Inflammation
Fever
Protective proteins
Natural killer cells
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Nonspecific Immunity (cont’d.)
• Phagocytosis:
– Phagocyte’s plasma membrane sends out
pseudopods to surround pathogen
– Pathogen is captured when pseudopods fuse
– Lysosomal membrane fuses with pathogen
– Potent enzymes are released to destroy
pathogen
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Nonspecific Immunity (cont’d.)
• Inflammation: responses the body makes
when confronted by an irritant
– Signs of inflammation: redness, heat, swelling,
pain
– Infection: inflammation caused by pathogenic
irritant
– Histamine: released by cells when tissues are
injured or irritated
– Pus: thick,Copyright
yellowish
accumulation of dead
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leukocytes, pathogens,
injured cells, and tissue
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Nonspecific Immunity (cont’d.)
• Fever: abnormal elevation in body
temperature
– Pyrogens: fever-producing substances released
by phagocytes; stimulate the hypothalamus to
reset the body’s temperature and produce a
fever
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Nonspecific Immunity (cont’d.)
• Protective proteins:
– Interferons: group of proteins secreted by cells
infected by a virus
– Complement proteins: attach to outer
membrane of bacterium to fill it with fluid and
electrolytes, causing lysis; enhance
phagocytosis and inflammatory response
• Natural killer (NK) cells: special types of
lymphocytes that act nonspecifically to kill
various cells
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Specific Immunity
• Third line of defense:
– Lymphocytes
• T lymphocytes
• B lymphocytes
– Macrophages
• Antigen: substance that stimulates the
formation of antibodies
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Specific Immunity (cont’d.)
• Lymphocytes:
– T lymphocytes (T cells):
• Thymus-derived lymphocytes
• Live and work in lymphoid tissue and circulate
in blood
• Comprise 70% to 80% of the blood’s lymphocytes
• Attack antigens directly through cell-to-cell contact, or
cell-mediated immunity
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Specific Immunity (cont’d.)
Cellmediated
immunity.
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Specific Immunity (cont’d.)
• T cells: cell-mediated immunity
– Killer T cells: punch holes in pathogen’s cell membrane
and secrete lymphokines that enhance phagocytic activity
– Helper T cells: secrete a lymphokine that stimulates T
cells and B cells and enhances immune response
– Suppressor T cells: inhibit immune response when the
antigen has been destroyed
– Memory T cells: remember the initial encounter with an
antigen and quickly reproduce and allow a faster immune
response in subsequent encounters
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Specific Immunity (cont’d.)
• Lymphocytes:
– B lymphocytes (B cells):
•
•
•
•
Liver and bone marrow-derived lymphocytes
Live and work in lymphoid tissue and circulate in blood
Comprise 20% to 30% of the blood’s lymphocytes
Interact with antigens indirectly through the secretion of
antibodies, or antibody-mediated immunity
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Specific Immunity (cont’d.)
Antibodymediated
immunity.
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Specific Immunity (cont’d.)
• B cells: antibody-mediated immunity
– Immunoglobulins: antibodies secreted by B cells
found in the gamma globulin part of plasma
proteins
– Three most abundant types of immunoglobulin:
• Immunoglobulin G (IgG)
• Immunoglobulin A (IgA)
• Immunoglobulin M (IgM)
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Specific Immunity (cont’d.)
• Antigen-antibody reaction: antibodies bind to
antigens and react with antigens directly
• Agglutination: the clumping together of the
antigen-antibody components
• Activated complement proteins: stimulate
chemotaxis, promote agglutination, make
pathogens more susceptible to phagocytosis,
and encourage lysis
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Specific Immunity (cont’d.)
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Types of Immunity
• Two main categories of immunity:
– Genetic immunity: genetic information
conveys immunity to certain diseases
– Acquired immunity: received during
person’s lifetime, either naturally or
artificially
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Types of Immunity (cont’d.)
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Acquired Immunity
• Naturally acquired immunity
– Active immunity: antibodies and memory cells
are produced in the body after first exposure to
a specific pathogen
– Passive immunity: antibodies that were
developed in response to the pathogens the
mother encountered in her life are passed to a
fetus by the mother
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Acquired Immunity (cont’d.)
• Artificially acquired immunity
– Active immunity:
• Vaccine: antigen-bearing substance injected into a
person to stimulate antibody production
– Passive immunity:
• Immune globulin: obtained from a donor that has
developed the antibodies in response to a specific
antigen
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Other Immunologic Responses
• Allergic reactions: immune system forms
antibodies to substances not usually
recognized as foreign
– Delayed-reaction allergy
– Immediate hypersensitivity reaction
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Other Immunologic Responses
(cont’d.)
Immediate
reaction
allergy.
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Other Immunologic Responses
(cont’d.)
• Autoimmune diseases: develop in response
to self attack, or autoimmunity
• Organ rejection: recipient’s immune system
recognizes donated organ as foreign and
mounts an immune attack against it
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Review
WBCs for Immune Reactions
• monocytes - type of lymphocytes
– formed in bone marrow/transported where needed by
body
– become macrophages
• macrophage - phagocytic cell that protects body by
ingesting invading cells
• lymphocytes - major class of WBCs
– formed in lymphatic tissue
Lymphocytes
• T cells or T Lymphocytes
– mature in thymus gland
– Cell mediated immunity
• B cells or B Lymphocytes
– mature in bone marrow
– antibody-mediated
immunity
T Cell or T Lymphocyte
(Cell Mediated Immunity)
• T Cell (cell mediated immunity)
–
–
–
–
–
circulating lymphocytes
produced in bone marrow
matures in thymus
live for years
primary function: coordinate immune defenses and kill
organisms
Lymphocyte: T Cells
• helper T cells - essential to proper functioning of
immune system
• Memory cells- remember antigens and stimulate a
faster response if same antigen introduced at a
later time
Immunity
• Immunity-state of being resistant or not
susceptible to a specific disease
• Acquired immunity-any form of immunity
NOT present at birth and obtained during
life
Factors That Influence Immune
System
• Health
• Age
• Heredity
Acquired Immune Deficiency
Syndrome (AIDS)
• Caused by HIV (Human Immunodeficiency Virus)
• HIV infects T-helper cells with often a long
incubation of up to 10 years
• AIDS name applied during advanced stages of
disease
• After immune system destroyed, opportunistic
infections occur.
Autoimmune Disorders
Antigens stimulate development of antibodies that
are unable to distinguish antigens of internal cells.
Body makes antibodies and T cells against itself and
attacks own tissues.
Multisystemic involvement.
Myasthenia gravis, rheumatoid arthritis
Infectious Mononucleosis
• Acute infection caused by virus.
• Fever, sore throat, swollen lymph glands, atypical
lymphocytes, splenomegaly, hepatomegaly,
abnormal liver function, and bruising.
• transmitted by droplet infection
• Infection confers permanent immunity
• Treatment symptomatic
Web sites
• Specific immunity
• http://science.nhmccd.edu/biol/inflam.html