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Chapter 22: The Lymphatic System Biology 142 A

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Identify, attack, and develop immunity to a specific pathogen ... pharyngeal tonsil (adenoid) 2 lingual tonsils. Lymphoid Organs. Lymph nodes. Thymus. Spleen ... – PowerPoint PPT presentation

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Title: Chapter 22: The Lymphatic System Biology 142 A


1
Chapter 22 The Lymphatic SystemBiology 142
APR.L. Brashear-Kaulfers
2
Pathogens
  • Microscopic organisms that cause disease
  • viruses
  • bacteria
  • fungi
  • parasites
  • Each attacks in a specific way

3
The Lymphatic SystemProtects us against disease
  • Lymphocytes
  • Lymphatic system cells respond to
  • environmental pathogens
  • toxins
  • abnormal body cells, such as cancers

4
What is the difference between nonspecific and
specific defense, and the role of lymphocytes
in the immune response?
5
Specific Defenses
  • Lymphocytes
  • part of the immune response
  • Identify, attack, and develop immunity to a
    specific pathogen
  • Immunity- The ability to resist infection and
    disease

6
The Immune System
  • All body cells and tissues involved in production
    of immunity
  • not just lymphatic system

7
Nonspecific Defenses
  • Block or attack any potential infectious organism
  • Cannot distinguish one attack from another

Immunity Nonspecific Defenses
PLAY
8
Organization of the Lymphatic System
What are the major components of the lymphatic
system and their functions?
Figure 221
9
4 Parts of the Lymphatic System
  • Lymph
  • a fluid similar to plasma
  • does not have plasma proteins
  • Lymphatic vessels (lymphatics)
  • network that carries lymph from peripheral
    tissues to the venous system
  • Lymphoid tissues and lymphoid organs
  • found throughout the body
  • Lymphocytes, phagocytes, and other immune system
    cells

10
Function of the Lymphatic System
  • To produce, maintain, and distribute lymphocytes-
  • Lymphocyte Production
  • - Lymphocytes are produced
  • in lymphoid tissues (e.g., tonsils)
  • lymphoid organs (e.g., spleen, thymus)
  • and in red bone marrow
  • Lymphocytes Distribution
  • detect problems
  • travel into site of injury or infection

11
Lymphocyte Circulation
  • From blood to interstitial fluid (lymph) through
    capillaries
  • Returns to venous blood through lymphatic vessels

12
The Circulation of Fluids
  • From blood plasma to lymph and back to the venous
    system
  • Also transports hormones, nutrients, and waste
    products

13
Lymphatic Vessels
  • Are vessels that carry lymph
  • Lymphatic system begins with smallest vessels
    lymphatic capillaries (terminal lymphatics)
  • Lymphatic Capillaries-
  • Differ from blood capillaries in 4 ways
  • start as pockets rather than tubes
  • have larger diameters
  • have thinner walls
  • flat or irregular in section

14
Lymphatic Capillaries
Endothelial cells loosely bound together with
overlap Overlap acts as one-way valve allows
fluids, solutes, viruses, and bacteria to
enter prevents return to intercellular space
Figure 222
15
Lacteals
  • Are special lymphatic capillaries in small
    intestine
  • Transport lipids from digestive tract

16
Lymphatic Vessels and Valves
Figure 223
17
Lymph Flow
  • From lymphatic capillaries to larger lymphatic
    vessels containing one-way valves
  • Lymphatic vessels travel with veins

18
Lymphatic Ducts and the Venous System
Figure 224
19
The Lymphatic System
  • Is divided into
  • 1) Superficial lymphatics - located in
  • skin
  • mucus membranes
  • serous membranes lining body
  • 2) Deep lymphatics- Are larger vessels that
    accompany deep arteries and veins

20
Superficial and Deep Lymphatics
  • Join to form large lymphatic trunks
  • Trunks empty into 2 major collecting vessels
  • thoracic duct
  • right lymphatic duct

21
The Inferior Thoracic Duct
  • Collects lymph from
  • left bronchiomediastinal trunk
  • left subclavian trunk
  • left jugular trunk
  • Empties into left subclavian vein
  • The Right Lymphatic Duct
  • Collects lymph from
  • right jugular trunk
  • right subclavian trunk
  • right bronchiomediastinal trunk
  • Empties into right subclavian vein

22
Lymphedema
  • Blockage of lymph drainage from a limb
  • Causes severe swelling
  • Interferes with immune system function

23
Why are lymphocytes important, and how are they
distributed in the body?
  • Lymphocytes
  • Make up 2030 of circulating leukocytes
  • Most are stored, not circulating

24
3 Classes of Circulating Lymphocytes
  • T cells thymus-dependent
  • Make up 80 of circulating lymphocytes
  • 2. B cells bonemarrow derived
  • Make up 1015 of circulating lymphocytes
  • Differentiate into plasma cells- Produce and
    secrete antibodies (immunoglobin proteins)
  • 3. NK cells
  • natural killer cells

25
3 Main Types of T Cells
  • Cytotoxic T cells-Attack cells infected by
    viruses
  • Produce cell-mediated immunity
  • 2. Helper T cells- Stimulate function of T cells
    and B cells
  • 3. Suppressor T cells-Inhibit function of T
    cells and B cells

26
Regulatory T Cells
  • Are helper and suppressor T cells
  • Control sensitivity of immune response
  • Other T Cells
  • Inflammatory T cells
  • Suppressor and inducer T cells

27
Antigens
  • Targets which identify any pathogen or foreign
    compound
  • Immunoglobin Proteins (Igs)
  • Also called antibodies (Ab)
  • The binding of a specific antibody to its
    specific target antigen initiates
    antibody-mediated immunity
  • - A chain of events which destroys the target
    compound or organism

28
Natural Killer (NK) Cells
  • Also called large granular lymphocytes
  • Make up 510 of circulating lymphocytes
  • Responsible for immunological surveillance
  • Attack
  • foreign cells
  • virus-infected cells
  • cancer cells

29
Lymphocyte Distribution
  • Tissues maintain different T cell and B cell
    populations
  • Lymphocytes wander through tissues
  • enter blood vessels or lymphatics for transport
  • can survive many years

30
Production and Distribution of Lymphocytes
Figure 225
31
Lymphopoiesis
  • Lymphocyte production involves
  • bone marrow
  • thymus
  • peripheral lymphoid tissues
  • Hemocytoblasts In bone marrow, divide into 2
    types of lymphoid stem cells

32
Lymphoid Stem Cells
  • Group 1
  • remain in bone marrow
  • produce B cells and natural killer cells
  • Group 2
  • migrate to thymus
  • produce T cells in environment isolated by
    blood-thymus barrier

33
T Cells and B Cells
  • Migrate throughout the body
  • to defend peripheral tissues
  • Retain their ability to divide
  • is essential to immune system function

34
Differentiation
  • B cells differentiate
  • with exposure to hormone interleukin-7
  • T cells differentiate
  • with exposure to several thymic hormones
  • Interleukin-7 - A cytokine produced by stromal
    cells in bone marrow

35
What are the structures and functions of
lymphoid tissues and organs?Lymphoid Tissues
Connective tissues dominated by lymphocytes
36
Lymphoid Nodules
Figure 226
37
Lymphoid Nodule
  • Areolar tissue with densely packed lymphocytes
  • Germinal center contains dividing lymphocytes

38
Distribution of Lymphoid Nodules
  • Lymph nodes
  • Spleen
  • Respiratory tract (tonsils)
  • Along digestive and urinary tracts

39
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

40
The 5 Tonsils
  • In wall of pharynx
  • left and right palatine tonsils
  • pharyngeal tonsil (adenoid)
  • 2 lingual tonsils

41
Lymphoid Organs
  • Lymph nodes
  • Thymus
  • Spleen
  • Are separated from surrounding tissues
  • By a fibrous connective-tissue capsule

42
Lymph Nodes
  • Range from 125 mm diameter

Figure 227
43
Afferent Lymphatic Vessels
  • Carry lymph
  • from peripheral tissues to lymph node
  • Efferent Lymphatic Vessels
  • Leave lymph node at hilus
  • Carry lymph to venous circulation

44
Lymph from Afferent Lymphatics
  • Flows through lymph node in a network of sinuses
  • From subcapsular sinus
  • contains macrophages and dendritic cells
  • Through outer cortex
  • contains B cells within germinal centers
  • Through deep cortex
  • dominated by T cells
  • Through the core (medulla)
  • contains B cells and plasma cells
  • organized into medullary cords
  • Into hilus and efferent lymphatics

45
Lymph Node
  • A filter
  • purifies lymph before return to venous
    circulation
  • Removes
  • debris
  • pathogens
  • 99 of antigens

46
Antigen Presentation
  • First step in immune response
  • Extracted antigens are presented to
    lymphocytes
  • or attached to dendritic cells to stimulate
    lymphocytes

47
Lymphoid Functions
  • Lymphoid tissues and lymph nodes
  • distributed to monitor peripheral infections
  • respond before infections reach vital organs of
    trunk

48
Lymph Nodes of Gut, Trachea, Lungs, and Thoracic
Duct
  • Protect against pathogens in digestive and
    respiratory systems
  • Lymph Glands
  • Large lymph nodes at groin and base of neck
  • Swell in response to inflammation

49
Lymphadenopathy
  • Chronic or excessive enlargement of lymph nodes
    may indicate infections, endocrine disorders, or
    cancer

50
The Thymus
Figure 228
51
The Thymus
  • Located in mediastinum
  • Deteriorates after puberty
  • diminishing effectiveness of immune system
  • Divisions of the Thymus Thymus is divided into 2
    thymic lobes
  • Septa divide lobes into smaller lobules

52
A Thymic Lobule
  • Contains a dense outer cortex
  • And a pale central medulla
  • Thymus Hormones
  • Thymosins
  • Promote development of lymphocytes

53
Lymphocytes
  • Divide in the cortex
  • T cells migrate into medulla
  • Mature T cells leave thymus by medullary blood
    vessels

54
Reticular Epithelial Cells in the Cortex
  • Surround lymphocytes in cortex
  • Maintain blood-thymus barrier
  • Secrete thymic hormones that stimulate
  • stem cell divisions
  • T cell differentiation

55
Reticular Epithelial Cells in the Medulla
  • Form concentric layers (Hassalls corpuscles)
  • The medulla has no bloodthymus barrier
  • T cells can enter or leave bloodstream

56
The Spleen
Figure 229
57
3 Functions of the Spleen
  • Removal of abnormal blood cells and other blood
    components by phagocytosis
  • Storage of iron recycled from red blood cells
  • Initiation of immune responses by B cells and T
    cells
  • in response to antigens in circulating blood

58
Structure of the Spleen
  • Attached to stomach by gastrosplenic ligament
  • Contacts diaphragm and left kidney
  • Splenic veins, arteries, and lymphatic vessels
  • communicate with spleen at hilus

59
Structure of the Spleen
  • Inside fibrous capsule
  • Red pulp contains many red blood cells
  • Contains elements of circulating blood plus
    fixed free macrophages
  • White pulp resembles lymphoid nodules

60
Trabecular Arteries
  • Branch and radiate toward capsule
  • Finer branches surrounded by white pulp
  • Capillaries discharge red blood cells into red
    pulp

61
Splenic Circulation
  • Blood passes through
  • network of reticular fibers
  • Then enters large sinusoids (lined by
    macrophages)
  • which empty into trabecular veins

62
Spleen Function
  • Phagocytes and other lymphocytes in spleen
  • identify and attack damaged and infected cells
  • in circulating blood

63
Body Defenses
  • Provide resistance to fight infection, illness,
    and disease
  • 2 categories of defenses
  • nonspecific defenses Always work the same way ,
    against any type of invading agent
  • specific defenses Protect against specific
    pathogens
  • Depend on activities of lymphocytes
  • Specific resistance (immunity)
  • develops after exposure to environmental hazards

64
7 Types of Nonspecific Resistance
  • Physical barriers
  • Phagocytic cells
  • Immunological surveillance
  • Interferons
  • Complement
  • Inflammation
  • Fever

65
Nonspecific and Specific Defenses
  • Operate together to provide resistance to
    infection and disease

66
The 7 Nonspecific Defenses
Figure 2210
67
The 7 Nonspecific Defenses
  • Physical Barriers -Keep hazardous materials
    outside the body
  • Phagocytes -Attack and remove dangerous
    microorganisms
  • Immunological Surveillance -Constantly monitors
    normal tissues
  • with natural killer cells (NK cells)
  • Interferons -Trigger production of antiviral
    proteins in normal cells
  • Antiviral proteins
  • do not kill viruses
  • block replication in cell

68
The 7 Nonspecific Defenses
  • Complement (C) Proteins -Form the complement
    system
  • Complements action of antibodies
  • Inflammation -Triggers a complex inflammatory
    response
  • Fever -A high body temperature
  • increases body metabolism
  • accelerates defenses
  • inhibits some viruses and bacteria

Immunity Complement
PLAY
69
What are the components and mechanisms of each
nonspecific defense?
70
Physical Barriers
  • Outer layer of skin
  • Hair
  • Epithelial layers of internal passageways
  • Secretions that flush away materials
  • sweat glands, mucus, and urine
  • Secretions that kill or inhibit microorganisms
  • enzymes, antibodies, and stomach acid

71
2 Classes of Phagocytes
  • Microphages neutrophils and eosinophils
  • Leave the bloodstream
  • Enter peripheral tissues to fight infections
  • Macrophages large phagocytic cells derived from
    monocytes
  • Distributed throughout body
  • Make up monocytemacrophage system
    (reticuloendothelial system)

72
Activated Macrophages
  • Respond to pathogens in several ways
  • engulf pathogen and destroy it with lysosomal
    enzymes
  • bind to pathogen so other cells can destroy it
  • destroy pathogen by releasing toxic chemicals
    into interstitial fluid

73
2 Types of Macrophages
  • Fixed macrophages - also called histocytes
    Microglia
  • found in central nervous system
  • Kupffer cells
  • found in liver sinusoids
  • Stay in specific tissues or organs
  • e.g., dermis and bone marrow
  • Free macrophages -Travel through blood stream
  • Special free macrophages
  • alveolar macrophages (phagocytic dust cells)

74
3 Functional Characteristics of Free Macrophages
and Microphages
  • Move through capillary walls (emigration)
  • Are attracted or repelled by chemicals in
    surrounding fluids (chemotaxis)
  • Phagocytosis begins
  • when phagocyte attaches to target (adhesion)
  • and surrounds it with a vesicle

75
Natural Killer Cell Function
Immunological Surveillance is carried out by
Natural killer (NK) cells
Figure 2211
76
NK Cell Function
  • Identifies and attaches to abnormal cell
    (non-selective)
  • Golgi apparatus in NK cell
  • forms perforin vesicles
  • Vesicles release perforin (exocytosis)
  • Perforin lyses abnormal cell membrane

77
NK Cells attack cancer cells and cells
infected with viruses
  • 1) Cancer Cells -with tumor specific antigens
  • are identified as abnormal by NK cells
  • some cancer cells avoid NK cells (immunological
    escape)
  • 2) Viral Infections Cells infected with
    viruses
  • present abnormal proteins on cell membranes
  • allow NK cells to identify and destroy them

78
Interferons
  • Proteins (cytokines) released by activated
    lymphocytes and macrophages-
  • Cytokines - Chemical messengers released by
    tissue cells
  • to coordinate local activities
  • to act as hormones to affect whole body

79
3 Types of Interferons
  • Alpha interferons
  • produced by leukocytes
  • stimulate NK cells
  • Beta interferons
  • secreted by fibroblasts
  • slow inflammation
  • Gamma interferons
  • secreted by T cells and NK cells
  • stimulate macrophage activity

80
Complement Activation
Complement Plasma contains 11 special complement
(C) proteins that complement antibody action
Figure 2212
81
Complement Activation
  • Complements work together in cascades
  • 2 pathways activate the complement system
  • classical pathway
  • alternative pathway

82
The Classical Pathway
  • Fast method
  • C1 binds to antibody molecule attached to antigen
    (bacterium)
  • Bound protein acts as enzyme
  • catalyzes chain reaction

83
The Alternative Pathway
  • Slow method
  • Exposed to antigen
  • factor P (properdin)
  • factor B
  • and factor D interact in plasma
  • Both pathways end with
  • conversion of inactive complement protein (C3)
  • to active form (C3b)

84
4 Effects of Complement Activation
  • Stimulation of inflammation
  • Attraction of phagocytes
  • Enhancement of phagocytosis by opsonization
  • complements working with antibodies (opsonins)
  • Destruction of target cell membranes
  • 5 complement proteins join to form membrane
    attack complex (MAC)

85
Inflammation
  • Also called inflammatory response
  • A localized response
  • Triggered by any stimulus that kills cells or
    injures tissue

86
Cardinal Signs and Symptoms
  • Swelling (tumor)
  • Redness (rubor)
  • Heat (calor)
  • Pain (dolor)

87
3 Effects of Inflammation
  • Temporary repair and barrier against pathogens
  • Retards spread of pathogens into surrounding
    areas
  • Mobilization of local and systemic defenses
  • and facilitation of repairs (regeneration)

88
Inflammation and Tissue Repair
Figure 2213
89
Inflammation and Tissue Repair
  • Injured cells release
  • prostaglandins
  • proteins
  • potassium ions
  • Changes interstitial environment and stimulates
    mast cells
  • Mast cells release
  • histamine (increases capillary permeability)
  • heparin (inhibits clotting

90
Inflammation and Tissue Repair
  • Increased blood flow
  • raises local temperature
  • causes area to swell, redden, and become painful
  • Blood clot forms around damaged area, isolating
    it
  • Complements
  • break down bacteria
  • attract phagocytes

91
Inflammation and Tissue Repair
  • Activated neutrophils attack debris and bacteria
  • Phagocytes and foreign proteins
  • activate bodys specific defense system
  • Macrophages clean up pathogens and cell debris
  • Fibroblasts form scar tissue

92
Products of Inflammation
  • Necrosis
  • local tissue destruction in area of injury
  • Pus
  • mixture of debris and necrotic tissue
  • Abscess
  • pus accumulated in an enclosed space

93
Fever - A maintained body temperature above 37C
(99F)
  • Pyrogens - Any material that causes the
    hypothalamus to raise body temperature
  • circulating pathogens, toxins, or antibody
    complexes
  • Endogenous Pyrogens Interleukin-1 (IL-1)
  • pyrogen released by active macrophages
  • a cytokine

94
Forms of Immunity
Figure 2214
95
Specific Defenses
  • Specific resistance (immunity)
  • responds to specific antigens
  • with coordinated action of T cells and B cells

96
T Cells
  • Provide cell-mediated immunity
  • Defends against abnormal cells and pathogens
    inside cells

97
B Cells
  • Provide antibody-mediated immunity
  • Defends against antigens and pathogens in body
    fluids

98
Forms of Immunity
  • 1) Innate Immunity
  • present at birth
  • 2) Acquired Immunity
  • after birth
  • Active
  • antibodies develop after exposure to antigen
  • Passive
  • antibodies are transferred from another source

99
Active Immunity
  • Naturally acquired
  • through environmental exposure to pathogens
  • Induced
  • through vaccines containing pathogens

100
Passive Immunity
  • Naturally acquired
  • antibodies acquired from the mother
  • Induced
  • by an injection of antibodies

101
4 Properties of Immunity
  • Specificity- Each T or B cell
  • responds only to a specific antigen, ignores all
    others
  • Versatility-The body produces many types of
    lymphocytes
  • each fights a different type of antigen (Ag)
  • active lymphocyte clones itself to fight specific
    Ag
  • Memory-Some active lymphocytes (memory cells)
  • stay in circulation
  • provide immunity against new exposure
  • Tolerance- Immune system ignores normal
    antigens

102
What are the differences between cell-mediated
(cellular) immunity and antibody-mediated
(humoral) immunity?
103
The Immune Response
Figure 2215 (Navigator)
104
The Immune Response
  • 2 main divisions
  • cell mediated immunity (T cells)
  • antibody mediated immunity (B cells)

Immunity Cell-Mediated Immunity
PLAY
105
What are the types of T cells and their
functions in the immune response?
106
What are the types of T cells and their
functions in the immune response?
  • 1) Cytotoxic T Cells also called Tc cells
  • Attack cells infected by viruses
  • Responsible for cell-mediated immunity
  • 2) Helper T Cells also called Th cells
  • Stimulate function of T cells and B cells
  • 3) Suppressor T Cells also called Ts cells
  • Inhibit function of T cells and B cells

107
Antigens and MHC Proteins
Antigens and MHC Proteins
PLAY
Figure 2216a (Navigator)
108
Antigen Recognition
  • T cells only recognize antigens that are bound to
    glycoproteins in cell membranes

109
Antigen Presentation
Figure 2216b
110
MHC Proteins
  • The membrane glycoproteins that bind to antigens
  • Genetically coded in chromosome 6
  • the major histocompatibility complex (MHC)
  • differs among individuals

111
2 Classes of MHC Proteins
  • Class I found in membranes of all nucleated
    cells
  • Pick up small peptides in cell and carry them to
    the surface
  • T cells ignore normal peptides
  • abnormal peptides or viral proteins activate T
    cells to destroy cell
  • Class II found in membranes of
    antigen-presenting cells (APCs)
  • found in lymphocytes Antigenic fragments
  • from antigenic processing of pathogens
  • bind to Class II proteins
  • inserted in cell membrane to stimulate T cells

112
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

113
Pinocytic APCs
  • Langerhans cells
  • in the skin
  • Dendritic cells
  • in lymph nodes and spleen

114
What are the mechanisms of T cell activation and
the differentiation of the major classes of T
cells?
115
An Overview of the Immune Response
Figure 2215 (Navigator)
116
Antigen Recognition
  • Inactive T cell receptors
  • recognize Class I or Class II MHC proteins
  • recognize a specific antigen
  • Binding occurs when MHC protein matches antigen

117
CD Markers
  • Also called cluster of differentiation markers
  • in T cell membranes
  • molecular mechanism of antigen recognition
  • more than 70 types
  • designated by an identifying number
  • CD3 Receptor Complex
  • Found in all T cells

118
CD8 Markers
  • Found on cytotoxic T cells and suppressor T cells
  • Respond to antigens on Class I MHC proteins
  • CD4 Markers
  • Found on helper T cells
  • Respond to antigens on Class II MHC proteins
  • CD8 or CD4 Markers - Bind to CD3 receptor complex
  • Prepare cell for activation

119
Costimulation
  • For T cell to be activated, it must be
    costimulated
  • by binding to stimulating cell at second site
  • which confirms the first signal

120
2 Classes of CD8 T Cells
  • Activated by exposure to antigens on MHC
    proteins
  • one responds quickly
  • producing cytotoxic T cells and memory T cells
  • the other responds slowly
  • producing suppressor T cells

121
Activation of Cytotoxic T Cells
Also called killer T cells Seek out and
immediately destroy target cells
Figure 2217 (Navigator)
122
Actions of Cytotoxic T Cells
  • Release perforin
  • to destroy antigenic cell membrane
  • Secrete poisonous lymphotoxin
  • to destroy target cell
  • Activate genes in target cell
  • that cause cell to die

123
Slow Response
  • Can take up to 2 days from time of first exposure
    to an antigen, for cytotoxic T cells to reach
    effective levels

124
Memory Tc Cells
  • Produced with cytotoxic T cells
  • Stay in circulation
  • Immediately form cytotoxic T cells
  • if same antigen appears again

125
Suppressor T Cells
  • Secrete suppression factors
  • Inhibit responses of T and B cells
  • After initial immune response
  • Limit immune reaction to single stimulus

126
Activation of Helper T Cells
Helper T Cells - Activated CD4 T cells divide
into active helper T cells secrete cytokines
memory T cells remain in reserve
Figure 2218
127
4 Functions of Cytokines
  • Stimulate T cell divisions
  • produce memory T cells
  • accelerate cytotoxic T cell maturation
  • Attract and stimulate macrophages
  • Attract and stimulate NK cells
  • Promote activation of B cells

128
Pathways of T Cell Activation
Figure 2219
129
KEY CONCEPT
  • Cell-mediated immunity involves close physical
    contact between activated Tc cells and foreign,
    abnormal or infected cells
  • T cell activation usually involves
  • antigen presentation by phagocytic cell
  • costimulation by cytokines from active phagocytes
  • Tc cells may destroy target cells through local
    release of cytokines, lymphotoxins, or perforin

130
What are the mechanisms of B cell activation and
the differentiation of plasma cells and memory B
cells?
131
B Cells
  • Responsible for antibody-mediated immunity
  • Attack antigens by producing specific antibodies
  • Millions of populations, each with different
    antibody molecules

Immunity Antibody-Mediated Immunity
PLAY
132
B Cell Sensitization
  • Corresponding antigens in interstitial fluids
    bind to B cell receptors
  • B cell prepares for activation
  • Preparation process is sensitization

133
B Cell Sensitization and Activation
During sensitization, antigens are taken into
the B cell, processed, reappear on surface,
bound to Class II MHC protein
PLAY
Figure 2220 (Navigator)
134
Helper T Cells
  • Sensitized B cell is prepared for activation, but
    needs helper T cell activated by same antigen
  • B Cell Activation
  • Helper T cell binds to MHC complex
  • secretes cytokines that promote B cell activation
    and division

135
B Cell Division
  • Activated B cell divides into
  • plasma cells -Synthesize and secrete antibodies
    into interstitial fluid
  • Memory B cells- Like memory T cells remain in
    reserve to respond to next infection

136
Antibody Structure
What is the structure of an antibody, and what
types of antibodies are found in body fluids and
secretions
Figure 2221a, b
137
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-Determine specificity of
    antibody molecule

138
5 Heavy-Chain Constant Segments
  • Determine 5 types of antibodies
  • IgG
  • IgE
  • IgD
  • IgM
  • IgA

139
Binding Sites
  • Free tips of 2 variable segments
  • form antigen binding sites of antibody molecule
  • which bind to antigenic determinant sites of
    antigen molecule

140
Antibody Function
  • AntigenAntibody Complex An antibody bound to
    an antigen

Figure 2221c, d
141
A Complete Antigen
  • Has 2 antigenic determinant sites
  • Binds to both of antigen binding sites of
    variable segments of antibody
  • Exposure to a complete antigen leads to
  • B cell sensitization
  • immune response

142
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

143
5 Classes of Antibodies
Table 221
144
5 Classes of Antibodies
  • Also called immunoglobins (Igs)
  • Are found in body fluids
  • Are determined by constant segments
  • Have no effect on antibody specificity

145
7 Functions of AntigenAntibody Complexes
  • Neutralization of antigen binding sites
  • Precipitation and agglutination
  • formation of immune complex
  • Activation of complement
  • Attraction of phagocytes
  • Opsonization
  • increasing phagocyte efficiency
  • Stimulation of inflammation
  • Prevention of bacterial and viral adhesion

146
KEY CONCEPT
  • Antibody-mediated immunity involves the
    production of specific antibodies by plasma cells
    derived from activated B cells
  • B cell activation usually involves
  • antigen recognition, through binding to surface
    antibodies, costimulation by a Th cell
  • Antibodies produced by active plasma cells bind
    to target antigen and
  • inhibit its activity or destroy it
  • remove it from solution
  • promote its phagocytosis by other defense cells

147
Primary and Secondary Responses
  • Occur in both cell-mediated and antibody-mediated
    immunity

Figure 2222
148
Primary and Secondary Responses to Antigen
Exposure
  • First exposure
  • produces initial response (Primary)
  • Next exposure
  • triggers secondary response
  • more extensive and prolonged
  • memory cells already primed

149
The Primary Response
  • Takes time to develop
  • Antigens activate B cells
  • Plasma cells differentiate
  • Antibody titer slowly rises
  • Peak response
  • can take 2 weeks to develop
  • declines rapidly
  • IgM
  • is produced faster than IgG
  • is less effective

150
The Secondary Response
  • Activates memory B cells
  • at lower antigen concentrations than original B
    cells
  • secrete antibodies in massive qualities
  • Effects of Memory B Cell Activation
  • IgG
  • rises very high and very quickly
  • can remain elevated for extended time
  • IgM
  • production is also quicker
  • slightly extended

151
KEY CONCEPT
  • Immunization produces a primary response to a
    specific antigen under controlled conditions
  • If the same antigen appears at a later date, it
    triggers a powerful secondary response that is
    usually sufficient to prevent infection and
    disease

152
Summary of the Immune Response
  • Specific and nonspecific defenses

Figure 2223
153
Body Responses to Bacterial Infection
Figure 2224
154
Combined Immune System Responses
Figure 2225
155
Combined Responses to Bacterial Infection
  • Neutrophils and NK cells begin killing bacteria
  • Cytokines draw phagocytes to area
  • Antigen presentation activates
  • helper T cells
  • cytotoxic T cells
  • B cells activate and differentiate
  • Plasma cells increase antibody levels

156
Combined Responses to Viral Infection
  • Similar to bacterial infection
  • But cytotoxic T cells and NK cells are activated
    by contact with virus-infected cells

157
Summary Cells of the Immune System
Table 222
158
KEY CONCEPT
  • Viruses replicate inside cells, whereas bacteria
    may live independently
  • Antibodies (and administered antibiotics) work
    outside cells, so are primarily effective against
    bacteria rather than viruses
  • Antibiotics cannot fight the common cold or flu
  • T cells, NK cells, and interferons are the
    primary defense against viral infection

159
What is the origin, development, activation, and
regulation of normal resistance to disease?
160
Immune System Development
  • Fetus can produce immune response or
    immunological competence
  • after exposure to antigen
  • at about 34 months

161
Development of Immunological Competence
  • Fetal thymus cells migrate to tissues that form T
    cells
  • Liver and bone marrow produce B cells
  • 4-month fetus produces IgM antibodies

162
Before Birth
  • Maternal IgG antibodies
  • pass through placenta
  • provide passive immunity to fetus
  • After Birth
  • Mothers milk provides IgA antibodies
  • while passive immunity is lost

163
Normal Resistance
  • Infant produces IgG antibodies through exposure
    to antigens
  • Antibody, B-cell, and T-cell levels slowly rise
    to adult levels
  • about age 12

164
Hormones of the Immune System
Table 223
165
6 Groups of Hormonal Cytokines
  • Interleukins
  • Interferons
  • Tumor necrosis factors
  • Chemicals that regulate phagocytic activities
  • Colony stimulating factors
  • Miscellaneous cytokines

166
What are the origins of autoimmune disorders,
immunodeficiency diseases, and allergies, and
what are some examples of each?
167
Immune Disorders
  • Autoimmune disorders- A malfunction of system
    that recognizes and ignores normal antigens
  • Activated B cells make autoantibodies against
    body cells
  • Immunodeficiency disease-
  • Thyroiditis
  • Rheumatoid arthritis
  • Insulin-dependent diabetes mellitus
  • Allergies -

168
Immunodeficiency Diseases
  • Problems with embryological development of
    lymphoid tissues
  • can result in severe combined immunodeficiency
    disease (SCID)
  • Viral infections such as HIV
  • can result in AIDS
  • Immunosuppressive drugs or radiation treatments
  • can lead to complete immunological failure

169
Allergies
  • Inappropriate or excessive immune responses to
    antigens
  • Allergens
  • antigens that trigger allergic reactions

170
4 Categories of Allergic Reactions
  • Type I
  • immediate hypersensitivity
  • Type II
  • cytotoxic reactions
  • Type III
  • immune complex disorders
  • Type IV
  • delayed hypersensitivity

171
Type I Allergy (1)
  • 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)
  • Sensitization leads to
  • production of large quantities of IgE antibodies
  • distributed throughout the body
  • Second exposure leads to
  • massive inflammation of affected tissues

172
Type I Allergy (2)
  • Severity of reaction depends on
  • individual sensitivity
  • locations involved
  • Allergens in blood stream may cause anaphylaxis

173
Anaphylaxis
  • Can be fatal
  • Affects cells throughout body
  • Changes capillary permeability
  • produce swelling (hives) on skin
  • Smooth muscles of respiratory system contract
  • make breathing difficult
  • Peripheral vasodilatation
  • can cause circulatory collapse (anaphylactic
    shock)

174
Antihistamine Drugs
  • Block histamine released by MAST cells
  • Can relive mild symptoms of immediate
    hypersensitivity

175
Stress and the Immune Response
  • Glucocorticoids
  • secreted to limit immune response
  • long-term secretion (chronic stress)
  • inhibits immune response
  • lowers resistance to disease

176
Functions of Glucocorticoids
  • Depression of the inflammatory response
  • Reduction in abundance and activity of phagocytes
  • Inhibition of interleukin secretion

177
Aging and the Immune Response
  • Immune system deteriorates with age, increasing
    vulnerability to infections and cancer

178
4 Effects of Aging on Immune Response
  • Thymic hormone production
  • greatly reduced
  • T cells
  • become less responsive to antigens
  • Fewer T cells reduce responsiveness of B cells
  • Immune surveillance against tumor cells declines

179
Integration with Other Systems
Nervous and Endocrine Systems Interact with
thymic hormones Adjust sensitivity of immune
Figure 2227
180
Disorders of the Lymphatic System
  • 3 categories affect immune response
  • disorders resulting from
  • an insufficient immune response
  • an inappropriate immune response
  • an excessive immune response

181
SUMMARY (1)
  • Divisions of the lymphatic system
  • lymphatic vessels (lymphatics)
  • lymph
  • lymphoid tissues and organs
  • Types of lymphocytes
  • T cells
  • B cells
  • NK cells
  • Lymphoid tissues and organs
  • Nodules nodes
  • MALT thymus
  • spleen

182
SUMMARY (2)
  • 7 nonspecific defenses
  • physical barriers
  • phagocytes
  • immunological surveillance
  • interferons
  • complement
  • inflammation
  • fever

183
SUMMARY (3)
  • Specific defenses
  • cell-mediated immunity
  • antibody mediated immunity
  • Forms of immunity
  • innate or acquired
  • active or passive
  • Properties of immunity
  • specificity, versatility, memory, andtolerance

184
SUMMARY (4)
  • T cells and cell-mediated immunity
  • antigen presentation
  • MHCs and APCs
  • antigen recognition
  • CD8 T cell activation
  • CD4 T cell activation

185
SUMMARY (5)
  • B cells and antibody-mediated immunity
  • sensitization
  • plasma cells and memory B cells
  • antibody structure
  • antigenantibody complex
  • 5 classes of immunoglobins

186
SUMMARY (6)
  • Primary and secondary responses to antigen
    exposure
  • Hormones and the immune system
  • interleukins, interferons, TNFs, and CSFs
  • Immune disorders
  • Effects of aging on the immune response
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