With treatment, the onset of AIDS can sometimes be
postponed for many years. Once AIDS develops in these
is the difference between HIv and AIDS?
does HIv replicate?
individuals, continued treatment can help them survive
with fewer complications for 4 to 10 years.
are the major symptoms that a patient ex-
periences during the initial infection with HIv?
does a reverse transcriptase inhibitor treat
omponents of the Lymphatic
System Are Found Throughout the
• 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
Red bone marrow
Left subclavian vein
364 CHAPTER 12
The Lymphatic System and Immunity