Biol 155 Human Physiology - University of British Columbia
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Transcript Biol 155 Human Physiology - University of British Columbia
Lymphatic System and
Immunity:
Lymphatic System
Lymph
Lymphatic vessels
Lymphatic tissue
Lymphatic nodules
Lymph nodes
Tonsils
Spleen
Thymus
Lymphatic Vessels
Carry lymph away from tissues
Lymphatic capillaries
More permeable than blood capillaries
Epithelium functions as series of one-way valves
Functions of the Lymphatic
System
Fluid balance
Fat absorption
Excess interstitial fluid enters lymphatic
capillaries and becomes lymph
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
Lymphatic Vessels
Carry lymph away from tissues
Lymphatic capillaries
More permeable than blood capillaries
Epithelium functions as series of one-way valves
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
Lymph Drainage Into Veins
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
Tonsils
Large groups of lymphatic
nodules in nasopharynx
and oral cavity
Provide protection against
bacteria and other harmful
material
Groups
Palatine
Pharyngeal
Lingual
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
Spleen
Located in left superior side of abdomen
Blood flows through at 3 different rates
Can be ruptured in traumatic abdominal injuries
resulting in bleeding, shock, death
Fast (most), slow, intermediate
Functions
Destroys defective RBCs
Detects and responds to foreign substances
Limited reservoir for blood
Spleen
Thymus
Located in superior mediastinum
Divisions: Cortex and medulla
Site of maturation of T cells
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
Innate immunity
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
Inflammatory Response
Normal Microcirculation Flow
Exudate Formation
Leukocyte Margination and Migration
Diapedesis
Chemotaxis
Innate Immunity: Cells
White blood cells
Most important cellular
components of immune
system
Methods
Chemotaxis
Phagocytosis
Phagocytic and first
cells to enter infected
tissue
Promote inflammation
Eosinophils
Monocytes that leave
blood, enter tissues
Large phagocytic cells
Basophils and mast cells
Neutrophils
Macrophages
Reduce inflammation
Natural killer cells
Lyse tumor and virusinfected cells
Antigenic Determinants
Antigenic determinants
Specific regions of a given
antigen recognized by a
lymphocyte
Antigenic receptors
Surface of lymphocyte
that combines with
antigenic determinant
C3a stimulates mast cells
and basophils, which
then secrete
inflammatory mediators
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
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
Origin and Development
of Lymphocytes
Positive selection
Negative selection
Eliminates lymphocytes that react against self-antigens
Primary lymphatic organs (red bone marrow, thymus)
Ensures survival of lymphocytes that react against
antigens
Where lymphocytes mature into functional cells
Secondary lymphatic organs
Where lymphocytes produce an immune response
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
Antigen Processing
MHC class I
Phagocytosis
Phagocytosis also involves membrane
invagination.
This process does not involve clathrin.
Pseudopods extend around a particle,
forming a phagosome.
Phagosome will fuse with a lysosome,
containing digestive enzymes.
There are smaller transport mechanisms
in the wall of the secondary lysosome.
Costimulation
Proliferation of Helper T Cells
Proliferation of B Cells
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
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
Actions of Antibodies
Antibody Production
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
Interactions and Responses of
Innate and Adaptive Immunity
Ways to Acquire
Adaptive Immunity
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
Immune System Problems
Hypersensitivity reactions
Autoimmune disease
Severe combined immunodeficiency disease
(SCID)
Transplantation
Acute rejection
Chronic rejection