What is the difference between nonspecific and specific defense, and the role of lymphocytes in...
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What is the difference between nonspecific
and specific defense, and the role of lymphocytes in the immune response?
????????? • The ability to resist infection and
disease
Immunity • The ability to resist infection and
disease
?????????? Defenses • Lymphocytes:
– part of the immune response • Identify, attack, and develop
immunity:– to a specific pathogen
Specific Defenses • Lymphocytes:
– part of the immune response • Identify, attack, and develop
immunity:– to a specific pathogen
Nonspecific Defenses • Block or attack any potential
infectious organism• Cannot distinguish one attack from
another
Immunity: Nonspecific DefensesPLAY
What are the major components of the
lymphatic system and their functions?
4 Parts of the Lymphatic System
What are they?
4 Parts of the Lymphatic System
1. Lymph: – a fluid similar to plasma– does not have plasma proteins
2. Lymphatic vessels (lymphatics): – network that carries lymph from
peripheral tissues to the venous system
4 Parts of the Lymphatic System
3. Lymphoid tissues and lymphoid organs:
– found throughout the body4. Lymphocytes, phagocytes, and
other immune system cells
Organization of the Lymphatic System
3D Rotation of the Lymphatic SystemPLAYFigure 22–1
Lymphocyte Production• 3 places that lymphocytes are
produced:
Lymphocyte Production• Lymphocytes are produced:
– lymphoid organs (e.g., spleen, thymus)
– and in red bone marrow– in lymphoid tissues (e.g., tonsils)
Lymphocyte Distribution• Lymphocytes:
– detect problems– travel into site of injury or infection
???????? • Are special lymphatic capillaries in
small intestine• Transport lipids from digestive
tract
Lacteals • Are special lymphatic capillaries in
small intestine• Transport lipids from digestive
tract
Figure 22–3
Lymphatic Vessels and Valves
??????????????• Blockage of lymph drainage from a
limb• Causes severe swelling• Interferes with immune system
function
Lymphedema• Blockage of lymph drainage from a
limb• Causes severe swelling• Interferes with immune system
function
Why are lymphocytes important, and how are they distributed in the
body?
Lymphocytes• Make up ????????????? % of
circulating leukocytes– Most are stored, not circulating
Lymphocytes• Make up 20–30% of circulating
leukocytes• Most are stored, not circulating
3 Classes of Circulating Lymphocytes
3 Classes of Circulating Lymphocytes
1. T cells:– thymus-dependent– Make up 80% of circulating
lymphocytes2. B cells:
– bone–marrow derived3. NK cells:
– natural killer cells
3 Main Types of T Cells
3 Main Types of T Cells1. Cytotoxic T cells2. Helper T cells3. Suppressor T cells
Cytotoxic T Cells• Attack cells infected by viruses• Produce cell-mediated immunity
Helper T Cells• Stimulate function of T cells and B
cells
Suppressor T Cells• Inhibit function of T cells and B
cells
“Regulatory T Cells”• Are helper and suppressor T cells• Control sensitivity of immune
response
B Cells • Make up 10–15% of circulating
lymphocytes• Differentiate into ???????????????
cells
B Cells • Make up 10–15% of circulating
lymphocytes• Differentiate into plasma cells
Plasma Cells• Produce and secrete ????????????
(immunoglobin proteins)
Plasma Cells• Produce and secrete antibodies
(immunoglobin proteins)
???????????? • Targets which identify any
pathogen or foreign compound
Antigens • Targets which identify any
pathogen or foreign compound
Natural Killer (NK) Cells • Also called large granular
lymphocytes • Make up 5–10% of circulating
lymphocytes
Natural Killer (NK) Cells • Responsible for immunological
surveillance• Attack:
– foreign cells– virus-infected cells– cancer cells
Figure 22–5
Production and Distribution of Lymphocytes
Lymphoid Stem Cells • Group 1:
– remain in bone marrow– produce B cells and natural killer cells
Lymphoid Stem Cells• Group 2:
– migrate to thymus– produce T cells in environment
isolated by blood-thymus barrier
T Cells and B Cells • Migrate throughout the body:
– to defend peripheral tissues• Retain their ability to divide:
– is essential to immune system function
What are the structures and functions of lymphoid
tissues and organs?
Lymphoid Tissues • Connective tissues dominated by
lymphocytes
Figure 22–6
Lymphoid Nodules
Lymphoid Nodule• Areolar tissue with densely packed
lymphocytes• Germinal center contains dividing
lymphocytes
Distribution of Lymphoid Nodules
• Lymph nodes• Spleen• Respiratory tract (tonsils)• Along digestive and urinary tracts
Mucosa-Associated Lymphoid Tissue (???????????????)
• Lymphoid tissues associated with the digestive system:– aggregated lymphoid nodules:
• clustered deep to intestinal epithelial lining
• Appendix:– mass of fused lymphoid nodules
Mucosa-Associated Lymphoid Tissue (MALT)
• Lymphoid tissues associated with the digestive system:– aggregated lymphoid nodules:
• clustered deep to intestinal epithelial lining
• Appendix:– mass of fused lymphoid nodules
The 5 ?????????? • In wall of pharynx:
– left and right palatine ??– pharyngeal ? (adenoid)– 2 lingual ??
The 5 Tonsils • In wall of pharynx:
– left and right palatine tonsils– pharyngeal tonsil (adenoid)– 2 lingual tonsils
Lymphoid Organs• Are separated from surrounding
tissues• By a fibrous connective-tissue
capsule – Lymph nodes– Thymus – Spleen
Figure 22–7
Lymph Nodes• Range from 1–25 mm diameter
??????????????• Chronic or excessive enlargement
of lymph nodes may indicate infections, endocrine disorders, or cancer
Lymphadenopathy• Chronic or excessive enlargement
of lymph nodes may indicate infections, endocrine disorders, or cancer
Antigen ????????????? • First step in immune response• Extracted antigens are
“presented” to lymphocytes:– or attached to dendritic cells to
stimulate lymphocytes
Antigen Presentation • First step in immune response• Extracted antigens are
“presented” to lymphocytes:– or attached to dendritic cells to
stimulate lymphocytes
The ??????????????• Located in mediastinum• Deteriorates after puberty:
– diminishing effectiveness of immune system
The Thymus• Located in mediastinum• Deteriorates after puberty:
– diminishing effectiveness of immune system
Figure 22–8
The Thymus
Thymus Hormones • ?????????????? • Promote development of
lymphocytes
Thymus Hormones • Thymosins • Promote development of
lymphocytes
Figure 22–9
3 Functions of the Spleen
3 Functions of the Spleen1. Removal of abnormal blood cells
and other blood components by phagocytosis
2. Storage of iron recycled from red blood cells
3 Functions of the Spleen3. Initiation of immune responses by
B cells and T cells:– in response to antigens in circulating
blood
What are the body’s nonspecific defenses and their functions?
SEVEN Nonspecific Defenses• Always work the same way • Against any type of invading agent
• ???????
7 Types of Nonspecific Resistance
1. Physical barriers2. Phagocytic cells3. Immunological surveillance4. Interferons5. Complement6. Inflammation7. Fever
Figure 22–10
The 7 Nonspecific Defenses
Complement (C) Proteins • Form the complement system • Complements action of antibodies
Immunity: ComplementPLAY
What is specific resistance? What are the forms and properties of
immunity?
Figure 22–14
Forms of Immunity
Forms of Immunity• ?????????:
– present at birth• ?????????:
– after birth
Forms of Immunity• Innate:
– present at birth• Acquired
– after birth
Acquired Immunity • ????????:
– antibodies develop after exposure to antigen
• ????????:– antibodies are transferred from
another source
Acquired Immunity • Active:
– antibodies develop after exposure to antigen
• Passive:– antibodies are transferred from
another source
Active Immunity • ??????????? ?????????:
– through environmental exposure to pathogens
• ????????????:– through vaccines containing
pathogens
Active Immunity • Naturally acquired:
– through environmental exposure to pathogens
• Induced:– through vaccines containing
pathogens
Passive Immunity • Naturally acquired:
– antibodies acquired from the mother• Induced:
– by an injection of antibodies
What are the differences between cell-mediated
(cellular) immunity and antibody-mediated (humoral) immunity?
Figure 22–15 (Navigator)
The Immune Response
The Immune Response• 2 main divisions:
– cell mediated immunity (??????? cells)– antibody mediated immunity (??????
cells)
Immunity: Cell-Mediated ImmunityPLAY
The Immune Response• 2 main divisions:
– cell mediated immunity (T cells)– antibody mediated immunity (B cells)
Immunity: Cell-Mediated ImmunityPLAY
What are the types of T cells and their functions
in the immune response?
Antigens and MHC Proteins
Antigens and MHC ProteinsPLAYFigure 22–16a (Navigator)
2 Classes of MHC Proteins• Class ???????:
– found in membranes of all nucleated cells
• Class ???????: – found in membranes of antigen-
presenting cells (APCs)– found in lymphocytes
2 Classes of MHC Proteins• Class I:
– found in membranes of all nucleated cells
• Class II: – found in membranes of antigen-
presenting cells (APCs)– found in lymphocytes
??????????? Cells (APCs)• Responsible for activating T cells
against foreign cells and proteins
Antigen-Presenting Cells (APCs)
• Responsible for activating T cells against foreign cells and proteins
Phagocytic APCs • Free and fixed macrophages:
– in connective tissues• Kupffer cells:
– of the liver• Microglia:
– in the CNS
Pinocytic APCs• Langerhans cells:
– in the skin• Dendritic cells:
– in lymph nodes and spleen
Actions of ??????????? T Cells 1. Release perforin:
– to destroy antigenic cell membrane 2. Secrete poisonous lymphotoxin:
– to destroy target cell3. Activate genes in target cell:
– that cause cell to die
Actions of Cytotoxic T Cells 1. Release perforin:
– to destroy antigenic cell membrane 2. Secrete poisonous lymphotoxin:
– to destroy target cell3. Activate genes in target cell:
– that cause cell to die
4 Functions of ??????????1. Stimulate T cell divisions:
– produce memory T cells– accelerate cytotoxic T cell maturation
2. Attract and stimulate macrophages
3. Attract and stimulate NK cells4. Promote activation of B cells
4 Functions of Cytokines1. Stimulate T cell divisions:
– produce memory T cells– accelerate cytotoxic T cell maturation
2. Attract and stimulate macrophages
3. Attract and stimulate NK cells4. Promote activation of B cells
??????????? Cells • Responsible for antibody-mediated
immunity• Attack antigens by producing
specific antibodies• Millions of populations, each with
different antibody molecules
Immunity: Antibody-Mediated ImmunityPLAY
B Cells • Responsible for antibody-mediated
immunity• Attack antigens by producing
specific antibodies• Millions of populations, each with
different antibody molecules
Immunity: Antibody-Mediated ImmunityPLAY
B Cell ?????????????• Corresponding antigens in
interstitial fluids bind to B cell receptors
• B cell prepares for activation• Preparation process is sensitization
B Cell Sensitization• Corresponding antigens in
interstitial fluids bind to B cell receptors
• B cell prepares for activation• Preparation process is sensitization
Figure 22–20 (Navigator)
B Cell Sensitization and Activation
B Cell Sensitization and ActivationPLAY
B Cell Sensitization• During sensitization, antigens are:
– taken into the B cell– processed– reappear on surface, bound to Class II
MHC protein
What is the structure of an antibody, and what
types of antibodies are found in
body fluids and secretions?
Figure 22–21a, b
Antibody Structure
Antibody Structure• 2 parallel pairs of polypeptide
chains: – 1 pair of heavy chains – 1 pair of light chains
• Each chain contains:– constant segments – variable segments
5 Heavy-Chain Constant Segments
• Determine 5 types of antibodies:– ??????????????????????
5 Heavy-Chain Constant Segments
• Determine 5 types of antibodies:– IgG– IgE– IgD– IgM– IgA
Figure 22–21c, d
Antibody Function
A ???????????? • Also called partial antigen • Must attach to a carrier molecule
to act as a complete antigen
A Hapten • Also called partial antigen • Must attach to a carrier molecule
to act as a complete antigen
Dangers of Haptens• Antibodies produced attack both
hapten and carrier molecule• If carrier is “normal”:
– antibody attacks normal cells– e.g., penicillin allergy
What are the functions of antibodies and how are they performed?
7 Functions of Antigen–Antibody Complexes
7 Functions of Antigen–Antibody Complexes 1. Neutralization of antigen binding
sites2. Precipitation and agglutination:
– formation of immune complex
7 Functions of Antigen–Antibody Complexes 3. Activation of complement4. Attraction of phagocytes5. Opsonization:
– increasing phagocyte efficiency
7 Functions of Antigen–Antibody Complexes 6. Stimulation of inflammation7. Prevention of bacterial and viral
adhesion
What are the primary and secondary responses
to antigen exposure?
Figure 22–22
Primary and Secondary Responses
• Occur in both cell-mediated and antibody-mediated immunity
The Primary Response • Peak response:
– can take 2 weeks to develop– declines rapidly
• IgM:– is produced faster than IgG– is less effective
The Secondary Response• Activates memory B cells:
– at lower antigen concentrations than original B cells
– secrete antibodies in massive qualities
Figure 22–24
Body Responses to Bacterial Infection
Figure 22–25
Combined
Immune System
Responses
Table 22–3
Hormones of the Immune System
???????????? Disorders • A malfunction of system that
recognizes and ignores “normal” antigens
• Activated B cells make autoantibodies against body cells
Autoimmune Disorders • A malfunction of system that
recognizes and ignores “normal” antigens
• Activated B cells make autoantibodies against body cells
Autoimmune Disorders • Thyroiditis• Rheumatoid arthritis• Insulin-dependent diabetes
mellitus
Immunodeficiency Diseases 3 examples (categories):
Immunodeficiency Diseases 1. Problems with embryological
development of lymphoid tissues:– can result in severe combined
immunodeficiency disease (SCID)
Immunodeficiency Diseases 2. Viral infections such as HIV:
– can result in AIDS
Immunodeficiency Diseases 3. Immunosuppressive drugs or
radiation treatments:– can lead to complete immunological
failure
?????????????? • Inappropriate or excessive immune
responses to antigens• Allergens:
– antigens that trigger allergic reactions
Allergies • Inappropriate or excessive immune
responses to antigens• Allergens:
– antigens that trigger allergic reactions
4 Categories of Allergic Reactions
• ????
4 Categories of Allergic Reactions
• Type I:– immediate hypersensitivity
• Type II:– cytotoxic reactions
4 Categories of Allergic Reactions
• Type III:– immune complex disorders
• Type IV:– delayed hypersensitivity
Type I Allergy (1 of 3)• Also called immediate
hypersensitivity• A rapid and severe response to the
presence of an antigen• Most commonly recognized type of
allergy• Includes allergic rhinitis
(environmental allergies)
Type I Allergy (2 of 3)• Sensitization leads to:
– production of large quantities of IgE antibodies
– distributed throughout the body • Second exposure leads to:
– massive inflammation of affected tissues
Type I Allergy (3 of 3)• Severity of reaction depends on:
– individual sensitivity– locations involved
• Allergens in blood stream may cause anaphylaxis
Anaphylaxis (1 of 2)• Can be fatal• Affects cells throughout body• Changes capillary permeability:
– produce swelling (hives) on skin
Anaphylaxis (2 of 2)• Smooth muscles of respiratory
system contract:– make breathing difficult
• Peripheral vasodilatation:– can cause circulatory collapse
(anaphylactic shock)
What are the effects of stress on immune
function?
Stress and the Immune Response
• ???????????????????:– secreted to limit immune response – long-term secretion (chronic stress):
• inhibits immune response• lowers resistance to disease
Stress and the Immune Response
• Glucocorticoids:– secreted to limit immune response – long-term secretion (chronic stress):
• inhibits immune response• lowers resistance to disease
Functions of Glucocorticoids • Depression of the inflammatory
response • Reduction in abundance and
activity of phagocytes• Inhibition of interleukin secretion