With treatment, the onset of AIDS can sometimes be
postponed for many years. Once AIDS develops in these
1.
What
is the difference between HIv and AIDS?
2.
How
does HIv replicate?
individuals, continued treatment can help them survive
with fewer complications for 4 to 10 years.
3.
What
are the major symptoms that a patient ex-
periences during the initial infection with HIv?
4.
How
does a reverse transcriptase inhibitor treat
HIv infection?
THE PLANNER
Summary
I
omponents of the Lymphatic
System Are Found Throughout the
Body 340
• As show n, the ly m p h a tic system consists of
p rim a ry organs (red bone m arrow and the
thym us) w here lym p h o c y te s are produced and
s e co n d a ry organs (lym ph nodes, spleen, and
lym p h a tic nodules) w here th e lym phocytes
and o th e r cells reside and carry o u t im m une
reactions. The lym phatic system drains in te rsti-
tial fluid, protects th e body from invaders, and
transp orts lipids and lipid-soluble vitam ins.
• Lym ph is in te rstitial fluid th a t drains into
lym p h cap illaries. Lymph capillaries drain into
lym p h a tic vessels. Lymph then drains into
larger lym phatic vessels and lym phatic ducts,
and it ultim ately enters the venous system and
general circulation. Skeletal and respiratory
pum ps drive lym ph through th e lym ph vessels,
w h ile valves keep it m oving in one direction.
On th e path back to th e circulation, lym ph
passes throu gh lym p h nodes, w here th e fluid
is filtered and im m une reactions take place.
• The spleen is th e largest lym phatic organ. It
stores platelets and red blood cells, rem oves
w o rn-ou t blood cells, and produces blood cells
during fetal life.
The lymphatic system • Figure 12.1
Palatine tonsil
Submandibular node
Cervical node
Right internal
jugular vein
Right lymphatic
duct
Right subclavian
vein
Lymphatic vessel
Thoracic duct
Intestinal node
Large intestine
Red bone marrow
Lymphatic vessel
Left internal
jugular vein
Left subclavian vein
Thoracic duct
Axillary node
Spleen
Aggregated lymphatic
follicle
Small intestine
Iliac node
Inguinal node
364 CHAPTER 12
The Lymphatic System and Immunity
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