C irculation o f lym ph • Figure 12.3
Lymph drains from interstitial fluid
through lymphatic capillaries, which
in turn feed into larger lymphatic
vessels and ultimately flow back into
the cardiovascular system. Lymph and
interstitial fluid are chemically similar
to blood plasma but with less protein.
Each day, the lymphatic system returns
about 3 L
) of fluid fi ltered
from blood to maintain blood volume.
duct, right lymphatic duct)
empty lymph into the junction
of jugular and subclavian veins
of the cardiovascular system.
pass lymph to
from lymph nodes.
carry lymph from
blood capillaries to lymph
lymph and remove foreign
filtering, phagocytosis, and
Endothelial cells that make up
overlap like roof shingles.
• When interstitial fluid pressure exceeds lymph pressure
inside, the cells separate slightly, and fluid enters the
capillary like floodwater pushing open a door.
• When the lymph pressure exceeds the interstitial fluid
pressure, the cells close tightly, and lymph cannot
Blood plasma is
filtered from blood
Let’s take a closer look at the circulation of lymph in
Figure 1 2.3, which shows the relationship of lymphatic
vessels and lymph nodes to the cardiovascular system.
Notice the close-up of the structure of lymphatic cap-
illaries. This overlapping structure allows interstitial
fluid to flow into the lymphatic capillaries—but not out.
Figure 12.3 also shows that afferent lymphatic ves-
sels carry lymph from capillaries to nodes (step fc ), and
that efferent lymphatic vessels carry lymph away from
a node (step K ). Finally, the lymphatic vessels (step C )
empty lymph into the junction of the jugular and subcla-
vian veins of the cardiovascular system. (step ^5 )
As in the venous system, the pressure responsible for
lymph flow is generated by skeletal muscle pumps and re-
spiratory pumps (see Chapter 11).
Components of the Lymphatic System Are Found Throughout the Body
p r o c e ss