Download Chapter 2: Chemistry, Matter, and Life

Chapter 15:
The Lymphatic System
and Immunity
Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins
Taylor: Memmler’s Structure and Function of the Human Body
The Lymphatic System
• System of tissues and vessels
• Scattered throughout the body
• Services almost all regions
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Taylor: Memmler’s Structure and Function of the Human Body
Functions of the Lymphatic System
• Fluid balance
– Lymph fluid
• Protection from infection
– lymphocytes
• Absorption of fats
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Taylor: Memmler’s Structure and Function of the Human Body
The lymphatic
system in
relation to the
cardiovascular
system.
Lymphatic
vessels pick up
fluid in the
tissues and
return it to the
blood in
vessels near
the heart.
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Taylor: Memmler’s Structure and Function of the Human Body
Pathway
of
lymphatic
drainage
in the
tissues.
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Taylor: Memmler’s Structure and Function of the Human Body
Lymphatic Circulation
• One-way system
• Begins in tissues
• Ends in bloodstream
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Taylor: Memmler’s Structure and Function of the Human Body
Lymphatic Capillaries
• Capillary walls (endothelium) are flattened epithelial
cells
• More permeable than blood capillaries
• Overlapping cells form one-way valves
• Arise blindly (closed at one end)
• Lacteals absorb digested fats
– Fats are transported into lymphatic vessels until
lymph is added to the blood
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Taylor: Memmler’s Structure and Function of the Human Body
Lymphatic Vessels
• Thin walled, delicate
• Have a beaded appearance
• Superficial sets
• Deep sets
• Nodes
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Taylor: Memmler’s Structure and Function of the Human Body
Right Lymphatic Duct
• Short vessel
• Receives lymph that comes from superior right quadrant
– Right side of head, neck, thorax
• Empties into right subclavian vein
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Taylor: Memmler’s Structure and Function of the Human Body
Thoracic Duct
• Left lymphatic duct
• Larger of two vessels
• Receives lymph from all parts of the body except those
above the diaphragm on right side
• Cisterna chyli
– First portion
– Storage pouch
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Taylor: Memmler’s Structure and Function of the Human Body
Vessels and
nodes of the
lymphatic
system. (A)
Lymph nodes
and vessels of
the head. (B)
Drainage of
right lymphatic
duct and
thoracic duct
into subclavian
veins.
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Taylor: Memmler’s Structure and Function of the Human Body
Movement of Lymph
• Segments of vessels located between the valves
contract rhythmically
• Skeletal muscles compress vessels
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Taylor: Memmler’s Structure and Function of the Human Body
Lymphoid Tissue
• Distributed throughout the body
• Makes up specialized organs of lymphatic system
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Taylor: Memmler’s Structure and Function of the Human Body
Lymph Nodes
• Grouping
• Structure
–
–
Fibrous connective tissue
capsule from which partitions
(trabeculae) extend into nodes
substance
Afferent lymphatic vessel
• Hilum
–
Sinuses
–
Cords
–
Nodules
–
Medulla
–
Efferent lymphatic vessel
–
Cervical nodes
–
Axillary nodes
–
Mesenteric nodes
–
Inguinal nodes
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Taylor: Memmler’s Structure and Function of the Human Body
The Spleen
• Cleanses blood
– Filtration
– Phagocytosis
• Destroys old red blood cells
• Produces red blood cells before birth
• Is reservoir for blood
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Taylor: Memmler’s Structure and Function of the Human Body
Location of
lymph
tissue.
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Taylor: Memmler’s Structure and Function of the Human Body
The Thymus
• Plays key role in early immune system development
• Produces thymosin
– Develops T lymphocyte cells
– Promotes lymphocyte growth
– Promotes lymphoid tissue activity
• Shrinks after puberty
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Taylor: Memmler’s Structure and Function of the Human Body
The Tonsils
Remove contaminants and trap pathogens
• Palatine tonsils
• Pharyngeal tonsil (adenoids)
• Lingual tonsils
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Taylor: Memmler’s Structure and Function of the Human Body
Location of the tonsils.
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Taylor: Memmler’s Structure and Function of the Human Body
Other Lymphoid Tissue
• Appendix
• Mucosal-associated lymphoid tissue (MALT)-prevents
microorganisms from invading deeper tissues
– Peyer patches
• Gut-associated lymphoid tissue (GALT)
– Includes peyer patches, tonsils and appendix
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Taylor: Memmler’s Structure and Function of the Human Body
The Reticuloendothelial
System
Cells responsible for destroying worn-out blood cells, bacteria,
cancer cells and other harmful foreign substances
•Monocytes
– Develop into macrophages
•Macrophages
– Kupffer cells
• Located in the liver sinusoids
– Dust cells
• Ingest solid particles that enter the lungs
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Taylor: Memmler’s Structure and Function of the Human Body
Body Defenses Against Disease
• Types of general body defenses against disease
• Nonspecific defenses
– Effective against any harmful agent
• Specific defenses
– Effective against a certain agent only
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Taylor: Memmler’s Structure and Function of the Human Body
Nonspecific Defenses
Successive lines of defense
• Simple outer barriers
• More complicated responses
• Immunity (ultimate defense mechanism)
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Taylor: Memmler’s Structure and Function of the Human Body
Chemical and Mechanical Barriers
• Skin
• Mucous membranes
–
**Cilia
• Body secretions
–
Tears
–
Perspiration
–
Saliva
–
Digestive juices
• Reflexes
–
Sneezing
–
Coughing
–
Vomiting
–
Diarrhea
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Taylor: Memmler’s Structure and Function of the Human Body
Phagocytosis
White blood cells take in and destroy waste and foreign
material
• Neutrophils
• Macrophages
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Taylor: Memmler’s Structure and Function of the Human Body
Natural Killer Cells
Type of lymphocyte
• Can recognize body cells with abnormal membranes
• Found in lymph nodes, spleen, bone marrow, blood
• Secrete protein that breaks down cell membrane
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Taylor: Memmler’s Structure and Function of the Human Body
Inflammation
Infection is inflammation caused by pathogens
• **Inflammatory reaction
– Heat, redness, swelling, pain
– Cells release histamine
– Leukocytes enter tissue
• Granulocytes, macrophages, mast cells
– Leukocytes and plasma produce inflammatory exudate
– Pus is produced
– Lymph nodes enlarge
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Taylor: Memmler’s Structure and Function of the Human Body
Fever
As phagocytes work, they release substances that raise
body temperature
• Stimulates phagocytes
• Increases metabolism
• Decreases some organisms’ ability to multiply
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Taylor: Memmler’s Structure and Function of the Human Body
Interferon
• Group of substances that prevent nearby cells from
producing more virus
– IFN a (alpha)
– IFN b (beta)
– IFN g (gamma)
• Also acts nonspecifically on immune system cells
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Taylor: Memmler’s Structure and Function of the Human Body
Specific Defenses—Immunity
• Power to overcome a specific disease agent
• Innate immunity
– Inherited in genes
• Adaptive immunity
– Develops after birth
– Acquired naturally or artificially
– Active or passive
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Taylor: Memmler’s Structure and Function of the Human Body
Types of
immunity
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Taylor: Memmler’s Structure and Function of the Human Body
Innate Immunity
Differences in physical constitution
• Species immunity
• Individual immunity
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Taylor: Memmler’s Structure and Function of the Human Body
Adaptive Immunity
Develops in a person
• During lifetime
• From encounters with specific harmful agents
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Taylor: Memmler’s Structure and Function of the Human Body
Antigens
• Foreign substances that
• Enter body
• Induce immune response of certain lymphocytes
– T cells
– B cells
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Taylor: Memmler’s Structure and Function of the Human Body
T Cells
• Originate in stem cells in bone marrow
• Change to T cells in thymus
• *Become sensitized to specific antigens
• Produce cell-mediated immunity
–
Cytoxic T cells
–
Helper T cells
–
Regulatory T cells
• Prevents overactivity
–
Memory T cells
• Macrophages
–
Phagocytic
–
Insert fragments of the foreign antigen into their plasma
membrane, antigen then displayued on the macrophages surface
in combination with antigens that a T cell can recognize as
belonging to the self
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Taylor: Memmler’s Structure and Function of the Human Body
B Cells and Antibodies
Antibody (Ab) also known as immunoglobulin (Ig) is
substance produced in response to antigen
• Manufactured by B cells (B lymphocytes)
• Must mature in fetal liver or in lymphoid tissue
• Provides humoral immunity
• Contained in gamma globulin fraction of blood plasma
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Taylor: Memmler’s Structure and Function of the Human Body
Activation of B
cells. The B cell
combines with
a specific
antigen. The
cell divides to
form plasma
cells, which
produce
antibodies.
Some of the
cells develop
into memory
cells, which
protect against
reinfection.
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Taylor: Memmler’s Structure and Function of the Human Body
The Antigen–Antibody Reaction
• Effects
–
Prevents attachment of pathogens
–
Causes clumping of antigen
–
Neutralizes toxins
–
Aids phagocytosis
–
Activates NK cells
–
Activates complement
• Group of enzymes
• Acts non-specifically
Promotes phagocytosis
Destroys cells
Promotes inflammation
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Taylor: Memmler’s Structure and Function of the Human Body
Naturally Adaptive Immunity
Immunity acquired through contact with a specific
disease organism
• Active immunity
• Passive immunity
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Taylor: Memmler’s Structure and Function of the Human Body
Figure 15-7 Nonspecific immunity.
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Taylor: Memmler’s Structure and Function of the Human Body
Artificial Adaptive Immunity
Vaccination (immunization) can cause a person’s
immune system to manufacture antibodies
• Preventive measure
• Risk of side effects
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Taylor: Memmler’s Structure and Function of the Human Body
Types of Vaccines
• Live
• Attenuated
• Toxoid
• Killed by heat or chemicals
• Antigenic component
• Genetically engineered
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Taylor: Memmler’s Structure and Function of the Human Body
Boosters
• Active immunity does not always last a lifetime
• Repeated inoculations (booster shots) help maintain
high titer of antibodies in the blood
• Number and timing varies with vaccines
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Taylor: Memmler’s Structure and Function of the Human Body
Passive Immunity
Acquired by administration of immune serum (antiserum)
• Short-lived immunity
• Used in emergencies
• Often derived from animals
• May cause sensitivity reaction
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