Immunology Notes
1. The Immune (Lymphatic) system: the body’s special defense response against
foreign organisms:
a. bacteria
b. viruses
c. transplants
d. transfusions
e. self
2. Comprised of two semi-independent parts
Lymph bathes the tissues of the body and the lymphatic vessels collect and move it
eventually back into the blood circulation
A. lymphatic vessels which transport fluids the have escaped from the vascular
system back to the blood
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special system of drainage vessels which weave between tissue
cells and blood capillaries of nearly all tissues
not found in bone, CNS, epidermis, skin, teeth, cartilage and
bone marrow.
Resolves problem of circulatory dynamics of lost fluids and
proteins into interstitial fluid
Takes in cell debris, pathogens and cancer cells
Lymphangitis: inflammation of lymphatic vessels: red lines
seen through skin that are tender
Right lymphatic duct drains from the right upper arm, right side
of the head and thorax
Thoracic duct drains the lymph from the rest of the body
a. Pumpless
b. Very low pressure
c. One way – only toward the heart
Lymphedema: severe localized edema as a result of anything
preventing normal return of lymph to blood i.e. tumors,
mastectomy
B. lymphoid tissues and organs: house phagocytic cells and lymphocytes
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lymph itself is comprised of water, plasma, ions and lymphoid
cells
Primary organs:
a.
Thymus gland: Found in the lower neck region and extends into thorax
* Size increases through adolescence; decreases
during
adulthood and by old age it atrophies and is
completely replaced by fatty tissues.
* Produces mature T cells. Immature thymoctyes
leave bone marrow and migrate into the thymus
* The mature T-cells are then released into the
bloodstream. The T-cells become immunocompetent
by the secretion of thymosin and thymopoietin.
b. Bone marrow: All the cells of the immune system are initially derived
from the bone marrow. – bone marrow derived stem cells differentiate
into either mature cells of the immune system or into precursors of cells
that migrate out the bone marrow to continue their maturation
elsewhere.
c. The bone marrow produces B cells, natural killer cells, granulocytes and
immature thymoctyes, in addition to red blood cells and platelets.
Secondary Organs:
d. Lymph nodes: found throughout the body
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kidney shaped and less the 2.5 cm in length
composed of T and B cells, macrophages,
found in inguinal, axillary, cervical regions, near
gastrointestional tract
filter antigens out of lymph
Lymph nodes can become swollen from infection, inflammatory conditions, an abscess
or cancer. Other causes of enlarged lymph nodes are rare. By far, the most common
cause of swollen lymph nodes is infection.
When swelling appears suddenly and is painful, it is usually caused by injury or an
infection. Enlargement that comes on gradually and painlessly may, in some cases
result from cancer of a tumor
Which lymph nodes are swollen depends on the type of problem and the body parts
involved. Identifying the location can help determine the possible cause
Swollen lymph nodes may also be caused by some medications (like phenytoin for
seizures) or certain vaccinations (namely typhoid).
b. spleen
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located in left side of abdominal cavity
largest lymphatic organ
extract aged, defective blood cells, platelets
removes debris, foreign matter, bacteria, viruses, toxins
stores breakdown products of RBCs for reuse
site of RBC production in fetus
stores platelets
splenectomy: surgical removal of spleen, macrophages in
liver and bone marrow take over function of the spleen
ix. B cells become activated and produce large amounts of
antibody – lymphocyte proliferation, immune surveillance
and response
c. tonsils and adenoids
i. ring of lymphatic tissue around the entrance to the
pharynx
ii. palatine, lingual, pharyngeal (adenoids)
iii. have invaginations called crypts that trap bacteria and
particulate matter
iv. filters and prevents pathogens from entering respiratory
and digestive systems
d. Peyer’s Patches
i. Lymph nodules found in distal potion of the ileum of the
small intestine
ii. Also concentrated in wall of appendix
iii. Similar to tonsils
iv. Destroy bacteria
v. Generate “memory” lymphocytes for long term immunity
e. Mucosa-Associated Lymphatic Tissue (MALT)
i. Peyer’s Patches, appendix nodules, tonsils, nodules in
bronchi
Key Points
ii. Major cells of the immune system (leukocytes/WBC’s)
arise and develop in primary organs
iii. Secondary organs are responsible for
1. filtering foreign substances
2. providing space for antigenic reactions