Download Memmler`s The Human Body in Health and Disease 11th

Memmler’s
The Human Body in Health and Disease
11th edition
Chapter 16
The Lymphatic System and
Lymphoid Tissue
To know better is to do better. Oprah Winfrey
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Functions of the Lymphatic System
• Fluid balance
– Lymph fluid
• Protection from infection
• Absorption of fats
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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.
What type of blood
vessel receives lymph
collected from the
body?
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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 called CHYLE
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Lymphatic Vessels
• Superficial sets
• Deep sets
• Nodes
• Right lymphatic duct
• Thoracic duct (left lymphatic duct)
– Cisterna chyli
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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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Lymphoid Tissue
• Distributed throughout the body
• Makes up specialized organs of lymphatic system
• Grouping
– Cervical nodes
– Axillary nodes
– Mesenteric nodes
– Inguinal nodes
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Structure of a lymph node.
(A) Arrows indicate the
flow of lymph through the
node. (B) Section of a
lymph node as seen under
the microscope (low
power). (B, Reprinted with
permission from Cormack
DH. Essential Histology.
2nd ed. Philadelphia:
Lippincott Williams &
Wilkins, 2001.)
What type of lymphatic
vessel carries lymph into a
node?
What type of lymphatic
vessel carries lymph out of
a node?
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The Spleen
• Cleanses blood
– Filtration
– Phagocytosis
• Destroys old red blood cells
• Produces red blood cells before birth
• Is a reservoir for blood
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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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Remove contaminants and trap pathogens
The Tonsils
– Palatine tonsils
– Pharyngeal tonsil (adenoids)
– Lingual tonsils
• Surgery to treat if recurrent infection or enlarged tonsils
make swallowing/breathing difficult
• Other Lymphoid Tissue -
Appendix
– Mucosal-associated lymphoid tissue (MALT)
• Peyer patches
– Gut-associated lymphoid tissue (GALT)
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The Reticuloendothelial
System
Cells responsible for destroying worn-out blood cells,
bacteria, cancer cells and other harmful foreign substances
•Monocytes
•Macrophages
– Kupffer cells (Liver)
– Dust cells (pulmonary macrophages)
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Disorders of the Lymphatic
System and Lymphoid Tissue
• Lymphangitis
• Septicemia
• Lymphadenitis
– Cervical
– Chronic
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Lymphedema
Tissue swelling due to obstruction of lymph flow
caused by
• Infection of lymphatic vessels
• Vessel blockage
– Malignant growth
– Parasites
• Loss of lymphatic vessels from injury or surgery
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Lymphadenopathy
Enlarged lymph nodes accompany certain diseases and
infections
•Acquired immunodeficiency syndrome (AIDS)
•Infectious mononucleosis
•Mumps
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Splenomegaly
Enlarged spleen accompanies certain diseases and
infections
•Scarlet fever
•Typhus fever
•Typhoid fever
•Syphilis
•Tropical parasitic diseases
•Splenic anemia
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Lymphoma
Any tumor in lymphoid tissue
• Malignant disease
– Hodgkin disease (has Reid- Sternberg cells)
– Non-Hodgkin lymphoma (does not have R-S cells)
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Body Defenses, Immunity, and Vaccines
• The Immune System
• 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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Why Do Infections Occur?
• Factors involved in infection
• Portal of entry
• Virulence of organism
– Aggressiveness
– Toxin production
• Dose (number) of pathogens
• Individual condition (predisposition) to infection
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Nonspecific Defenses
Successive lines of defense
• Simple outer barriers
• More complicated responses
• Immunity (ultimate defense mechanism)
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Chemical and Mechanical Barriers
• Skin
• Mucous membranes
–
Cilia
• Body secretions
–
Tears
–
Perspiration
–
Saliva
–
Digestive juices
• Reflexes
–
Sneezing
–
Coughing
–
Vomiting
–
Diarrhea
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Phagocytosis
White blood cells take in and destroy waste and foreign
material
• Neutrophils
• Macrophages
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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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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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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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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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Immunity
• Power to overcome a specific disease agent
• Innate immunity
– Inherited in genes
• Adaptive immunity
– Most develops after birth, during life time, in
response to encounters with specific harmful agents
– Acquired naturally or artificially
– Active or passive
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Antigens
• Foreign substances that enter body
• Induce immune response of certain lymphocytes
– T cells
– B cells
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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
– Memory T cells
• Macrophages
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Activation of a helper T cell by a macrophage (antigenpresenting cell).
What is contained in the lysosome that joins the phagocytic
vesicle?
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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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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.
•What two types of
cells develop from
activated B cells?
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4 Types of Immunity
Artificial Immunity
• Active – give a weak
antigen in a vaccine
form to make your
body WORK to build a
defense system
• Passive – already
exposed to antigen;
Nurse GIVES a premade immunoglobulin
for instant protection
Natural Immunity
• Active – get a virus
and the body has to
WORK to form
antibodies to virus
• Passive – mother
GIVES immunity to the
fetus before birth
You keep what you work to gain. LM 2011
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The Antigen–Antibody Reaction
Complement is the enzymatic activity of a group of
nonspecific proteins in blood that:
• Coats foreign cells
• Destroys cells
• Promotes inflammation
• Attracts phagocytes
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Types of Vaccines
• Live
• Attenuated
• Toxoid
• Killed by heat or chemicals
• Antigenic component
• Genetically engineered
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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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Disorders of the Immune
System
• Resulting from overactivity
– Allergy
– Autoimmune disease
• Resulting from underactivity
– Hereditary
– Infections
– Environmental
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AutoImmune
Abnormal reactivity to one’s own tissues
• Factors
– Disease
– Loss of immune system control
– Cross-reaction of antibodies and self antigens
• Treatments
– Immune-suppressing drugs
– Chemotherapy/stem cell replacement
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Immune Deficiency Diseases
Failure of immune system
• May involve any part of system
• Varies in severity
• Congenital or acquired (e.g., AIDS)
• HIV
– A retrovirus; uses reverse transcriptase enzyme
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Multiple Myeloma
Cancer of blood-forming bone marrow cells
• Effects of disease
–
Lowered resistance to infection
–
Anemia
–
Bone pain
–
Bone tissue loss
–
Kidney failure
• Treatment
–
Chemotherapy
–
Bone marrow transplants
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Transplantation and Rejection Syndrome
• Caused by normal antigen–antibody reaction
• Reduced by
– Tissue typing
– Immune suppression drugs
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•Questions?
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