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Chapter 15
THE LYMPHATIC SYSTEM
AND IMMUNITY
FUNCTIONS OF THE
LYMPHATIC SYSTEM
• Lymph fluid acts as intermediary
between blood, capillaries, and
tissues
• Lymph vessels transport tissue
fluid back into circulatory system
• Lymph nodes produce lymphocytes
and filter harmful bacteria
© 2004 Delmar Learning, a Division of Thomson Learning, Inc.
FUNCTIONS OF THE
LYMPHATIC SYSTEM
• Spleen produces lymphocytes and
monocytes, acts as a reservoir for
blood, and recycles red blood cells
• Thymus gland produces Tlymphocytes for immune system
© 2004 Delmar Learning, a Division of Thomson Learning, Inc.
LYMPH
• Lymph diffuses from capillaries
into tissue spaces
• Lymph acts as an intermediary
between blood in capillaries and
tissues
• Lymph carries digested food,
oxygen, and hormones to cells
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LYMPH VESSELS
• Lymph vessels accompany and are
similar to veins
• They are in almost all tissues and
organs that have blood vessels
• Lymph only travels in direction
from body organs to the heart
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LYMPH VESSELS
• 2 large main lymphatics
– Thoracic duct (left lymphatic duct)
• Receives lymph from left side of head,
neck, abdominal area, and lower limbs
– Right lymphatic duct
• Circulates lymph from right arm, right
side of head, and upper trunk to the
superior vena cava
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LYMPH NODES
• Lymph nodes provide sites for
lymphocyte production and screen
harmful substances from the lymph
• Bacteria and other harmful
substances in large quantities may
injure the lymph node
• Adenitis - swelling in lymph gland
© 2004 Delmar Learning, a Division of Thomson Learning, Inc.
LYMPH NODES
© 2004 Delmar Learning, a Division of Thomson Learning, Inc.
TONSILS
• Tonsils are masses of lymphatic
tissues capable of producing
lymphocytes and filtering bacteria
• Three pairs of tonsils
– Palatine
– Adenoids
– Lingual
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SPLEEN
• The spleen is a saclike mass of
lymphatic tissue that forms
lymphocytes and monocytes
• The spleen filters blood that
passes through it, destroying old or
fragile red blood cells
• The spleen stores large amounts of
red blood cells
© 2004 Delmar Learning, a Division of Thomson Learning, Inc.
THYMUS GLAND
• The thymus’s function is to produce
lymphocytes called T-lymphocytes
• The thymus is also an endocrine
gland because it secretes a
hormone called thymosin that
stimulates the production of
lymphoid cells
© 2004 Delmar Learning, a Division of Thomson Learning, Inc.
DISORDERS OF THE
LYMPH SYSTEM
• Lymphadenitis - enlargement of the
lymph nodes that occurs when
infection is present
• Hodgkin’s disease - form of cancer
of lymph nodes
• Infectious mononucleosis - caused
by Epstein-Barr virus
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IMMUNITY
• Immunity is the body’s ability to
resist invaders and disease
– Acquired immunity - reaction to
exposure of invaders
– Passive acquired immunity - borrowed
immunity from another person’s blood
that produces immunity immediately
© 2004 Delmar Learning, a Division of Thomson Learning, Inc.
IMMUNITY
– Active acquired immunity
• Natural acquired immunity results from
having had and recovering from disease
• Artificial acquired immunity is the result
of inoculation with vaccine, antigen, or
toxoid
– Immunization is increasing the
resistance to infection through
artificial means
© 2004 Delmar Learning, a Division of Thomson Learning, Inc.
IMMUNITY
• Autoimmunity
– Occurs when a person’s own immune
system targets normal cells, tissues,
and organs of person’s own body
– Causes range from genetics to viruses
to sunlight exposure
© 2004 Delmar Learning, a Division of Thomson Learning, Inc.
IMMUNITY
• Hypersensitivity
– Body’s immune system fails to protect
itself against foreign material
– Antibodies irritate certain body cells
– Allergen - antigen causes allergic
responses
• Anaphylactic shock - severe, often fatal
allergic reaction
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AIDS/HIV
•
•
•
•
Acquired - disease is not inherited
Immune - body’s natural defenses
Deficiency - lacks cellular immunity
Syndrome - diagnosed from sets of
diseases or conditions present
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AIDS/HIV
• Human immunodeficiency virus
(HIV) destroys T4-lymphocyte cells
without causing symptoms
• Opportunistic infections arise
• Three outcomes of HIV infection:
– AIDS
– AIDS-related complex (ARC)
– Asymptomatic infection
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AIDS/HIV
• Transmission of AIDS
– Sexual contact with infected partner
– Sharing hypodermic needles among IV
drug users
– In utero or at birth of infected
mother
– Transfusion of blood
© 2004 Delmar Learning, a Division of Thomson Learning, Inc.
AIDS/HIV
• Screening tests for HIV/AIDS
– There are two antibody tests
• Enzyme-linked immunosorbent assay
(ELISA) - detects antibodies for AIDS
but not the virus
• Western blot is the follow-up to confirm
ELISA results
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AIDS/HIV
• Symptoms of HIV/AIDS
– Flu-like symptoms
– Fever
– Headache
– Malaise
– Enlarged lymph glands
© 2004 Delmar Learning, a Division of Thomson Learning, Inc.
AIDS/HIV
• There is no cure for AIDS yet
certain drugs are used to slow the
virus
• Transmission is prevented by
following the CDC’s Standard
Precautions
© 2004 Delmar Learning, a Division of Thomson Learning, Inc.