Transcript chapt22_lecture

Anatomy and Physiology, Sixth Edition
Rod R. Seeley
Idaho State University
Trent D. Stephens
Idaho State University
Philip Tate
Phoenix College
Chapter 22
Lecture Outline*
*See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes.
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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Chapter 22
Lymphatic System and Immunity
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Lymphatic System
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Lymph
Lymphatic vessels
Lymphatic tissue
Lymphatic nodules
Lymph nodes
Tonsils
Spleen
Thymus
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Functions of the Lymphatic System
• Fluid balance
– Excess interstitial fluid enters lymphatic
capillaries and becomes lymph
• Fat absorption
– Absorption of fat and other substances from
digestive tract
• Defense
– Microorganisms and other foreign substances
are filtered from lymph by lymph nodes and
from blood by spleen
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Lymphatic Vessels
• Carry lymph away from tissues
• Lymphatic capillaries
– More permeable than blood capillaries
– Epithelium functions as series of one-way valves
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Lymphatic Vessels
• Lymphatic capillaries join to form
• Lymphatic vessels
– Have valves that ensure one-way flow
• Lymph nodes: Distributed along vessels and
filter lymph
• Lymphatic trunks: Jugular, subclavian,
bronchomediastinal, intestinal, lumbar
• Lymphatic ducts: Right and thoracic which
connect to large veins
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Lymph Drainage Into Veins
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Lymphatic Tissue and Nodules
• Lymphatic tissue
– Consists mainly of
lymphocytes
– Encapsulated or not
• Lymphatic nodules
– Numerous in loose
connective tissue of
digestive (Peyer’s
patches), respiratory,
urinary, reproductive
systems
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Tonsils
• Large groups of lymphatic
nodules in nasopharynx
and oral cavity
• Provide protection against
bacteria and other harmful
material
• Groups
– Palatine
– Pharyngeal
– Lingual
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Lymph Nodes
• Organized in cortex and medulla
• Substances removed by phagocytosis or stimulate
lymphocytes or both
• Only structures to filter lymph
– Afferent and efferent vessels
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Spleen
• Located in left superior side of abdomen
– Can be ruptured in traumatic abdominal injuries
resulting in bleeding, shock, death
• Blood flows through at 3 different rates
– Fast (most), slow, intermediate
• Functions
– Destroys defective RBCs
– Detects and responds to foreign substances
– Limited reservoir for blood
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Spleen
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Thymus
• Located in superior mediastinum
• Divisions: Cortex and medulla
• Site of maturation of T cells
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Immunity
• Ability to resist damage from foreign substances as
microorganisms and harmful chemicals
• Categories
– Innate or nonspecific resistance
• Mechanical mechanisms: Prevent entry or remove microbes
• Chemical mediators: Promote phagocytosis and inflammation
• Cells: Involved in phagocytosis and production of chemicals
– Adaptive or specific immunity
• Specificity: Ability to recognize a particular substance
• Memory: Ability to remember previous encounters with a
particular substance and respond rapidly
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Mechanical Mechanisms and
Chemical Mediators
• Mechanical Mechanisms
– Skin, tears, saliva, mucous
membranes, mucus
• Chemical Mediators
– Complement
• Group of 20 proteins
• Circulate in blood in
inactive form
• Become activated in
cascade form: Classical
or alternative pathway
– Interferons
• Prevent viral replication
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Complement Cascade
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Innate Immunity: Cells
• White blood cells
– Most important cellular
components of immune
system
– Methods
• Chemotaxis
• Phagocytosis
• Neutrophils
– Phagocytic and first
cells to enter infected
tissue
• Macrophages
– Monocytes that leave
blood, enter tissues
– Large phagocytic cells
• Basophils and mast cells
– Promote inflammation
• Eosinophils
– Reduce inflammation
• Natural killer cells
– Lyse tumor and virusinfected cells
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Inflammatory Response
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Inflammatory Response
• Tissue injury regardless of type can cause
inflammation
• Response initiated by chemical mediators that
produce vasodilation, chemotactic attraction,
increased vascular permeability
• Types
– Local: Symptoms are redness, heat, swelling, pain, loss of
function
– Systemic: Symptoms are increase in neutrophil numbers,
fever and shock
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Adaptive Immunity
• Involves the ability to recognize, respond to, and
remember a particular substance
• Stimulants
– Antigens: Large molecules
• Foreign: Not produced by body, introduced from outside
• Self-antigens: Produced by body
– Haptens: Small molecules and capable of combining
• Types
– Humoral or Antibody-mediated: B cells
– Cell-mediated: T cells
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Origin and Development
of Lymphocytes
• B and T cells
– Originate in red bone
marrow
– Move to lymphatic
tissue from processing
sites and continually
circulate
– Clones are small
groups of identical
lymphocytes
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Origin and Development
of Lymphocytes
• Positive selection
– Ensures survival of lymphocytes that react against
antigens
• Negative selection
– Eliminates lymphocytes that react against self-antigens
• Primary lymphatic organs (red bone marrow, thymus)
– Where lymphocytes mature into functional cells
• Secondary lymphatic organs
– Where lymphocytes produce an immune response
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Antigenic Determinants
• Antigenic determinants
– Specific regions of a
given antigen recognized
by a lymphocyte
• Antigenic receptors
– Surface of lymphocyte
that combines with
antigenic determinant
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Major Histocompatability
Complex (MHC)
• Most lymphocyte activation involves
glycoproteins of cell surfaces called MHC
molecules
– Class I molecules display antigens on surface of
nucleated cells, resulting in destruction of cells
– Class II molecules display antigens on surface
of antigen-presenting cells, resulting in
activation of immune cells
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Antigen Processing
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Costimulation
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Proliferation of Helper T Cells
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Proliferation of B Cells
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Lymphocyte Inhibition
• Tolerance: To prevent the immune system
from responding to self-antigens
– Provoked by
• Deletion of self-reactive lymphocytes
• Preventing activation of lymphocytes
• Activation of suppressor T cells
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Antibody-Mediated Immunity
• Antibodies or
Immunoglobulins (Ig)
– Classes: IgG, IgM,
IgA, IgE, IgD
– Structure
• Variable region: Part
that combines with
anitgenic determinant of
antigen
• Constant region:
Responsible for
activities
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Actions of Antibodies
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Antibody Production
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Cell-Mediated Immunity
• Antigen activates effector T cells and produces memory T cells
• Cytotoxic T cells lyse virus-infected cells, tumor cells, and
tissue transplants
• Cytotoxic T cells produce cytokines, which promote
phagocytosis and inflammation
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Interactions and Responses of
Innate and Adaptive Immunity
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Acquired Immunity
• Active natural immunity
– Results from natural exposure to an antigen
• Active artificial immunity
– Results from deliberate exposure to an antigen
• Passive natural immunity
– Results from transfer of antibodies from a mother to her
fetus or baby
• Passive artificial immunity
– Results from transfer of antibodies (or cells) from an
immune animal to a nonimmune one
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Ways to Acquire
Adaptive Immunity
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Effects of Aging
• Little effect on lymphatic system
• Decreased ability of helper T cells to
proliferate in response to antigens
• Decreased primary and secondary antibody
responses
• Decreased ability of cell-mediated
immunity to resist intracellular pathogens
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Immune System Problems
• Hypersensitivity reactions
• Autoimmune disease
• Severe combined immunodeficiency disease
(SCID)
• Transplantation
– Acute rejection
– Chronic rejection
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