The lymphatic system
is composed of blind-ended capillary beds
that are found adjacent to the venous part of blood system capillaries
. The lymph capillaries
feed into lymphatic vessels
that return the fluid to the venous circulation.
are lined with loosely overlapping endothelial cells
, making them extremely delicate. The endothelial cells
also overlap to form one-way minivalves
to allow the interstitial fluid
to freely enter the lymphatic system
, but not to exit. One-way valves
inside the capillaries
keep fluid flowing towards the lymphatic vessels
leading to the venous circulation.
Once the fluid has left the lymphatic capillaries
it flows into larger lymphatic collecting vessels
. The cisterna chyli
is an expanded collecting vessel that drains the digestive system
. The collecting vessels eventually join the venous system
at the right lymphatic duct
and thoracic duct
under the clavicle.