Lymphatic System
Functions
Returns excess tissue fluids to the circulatory system
Returns "leaking" blood proteins to the circulatory system
Fights infection and cancerous cells
Components
Lymph - the interstitial fluid expressed from the circulatory
capillaries and transported by the lymphatic vessels.
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Lymph Capillaries - located throughout the body near capillaries
of the circulatory system. These minute vessels have mini-valves that allow
fluid and some cells to enter but not exit. Constant influx of new material
is largely responsible for movement away from uptake sites.
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Lymph Collecting Vessels - lymph capillaries unite to form these
vessels that parallel circulatory arteries and veins but are much smaller
and possess comparatively thinner walls. Movement of lymph through these
collecting vessels is in part due to the contraction of smooth muscle in
the tunica media, body motion, and the pulsation of nearby arteries and
veins.
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Lymph Trunks - larger lymphatic vessels draining specific parts
of the body.
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Lymph Ducts
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Thoracic Duct - returns lymph to the circulatory system near the
junction of the external jugular and subclavian veins. This duct is found
in everyone.
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Right Lymphatic Duct - When this duct is present it returns lymph
from the upper right quarter of the body to the area near the junction
of the right external jugular and subclavian.
Lymph Nodes - occur throughout the body and may be as large as 1
inch in diameter. All lymph passes through at least one lymph node prior
to re-entering the circulatory system. These sites serve to combat bacteria
and cancerous cells, although they may become overwhelmed and swell.
Lymph Organs
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Spleen
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Thymus
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Tonsils
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Appendix