The Lymphatic System
Click on the links below
Check out the links and exercises at the bottom!
Introduction
to the Lymphatic System
The
Lymphatic System is the common name for the circulatory vessels or ducts in
which extra-cellular fluid of vertebrates (lymph) is collected and carried to
join the bloodstream. The
lymphatic system is important because it:
-
Transports digested fat from the intestine to the bloodstream
-
Removes and destroys toxic substances
-
Resists the spread of disease throughout the body.
The
portions of the lymphatic system that collect the tissue fluids are known as
lymphatic capillaries and are similar in structure to ordinary capillaries. The
lymphatic capillaries that pick up digested fat in the villi of the intestine
are known as lacteals.
Click
on the picture on the left for a larger version.
These
vessels are found in all body tissues except the central nervous system. The
lymphatic capillaries run together to form larger ducts (lymphatics) that
intertwine about the arteries and veins. The
muscular movements of the body move along the lymph in these lymphatics. (There
is no heart like pump). There
are valves in the lymphatics which stop the lymph from back flowing.
The
ducts from the lower limbs, abdomen and left arms come together at left side of
the body to form the thoracic duct.
Another,
smaller vessel, known as the right lymphatic duct, receives lymph from the right
side of the thorax, the right arm, and the right side of the head. Both these
vessels eventually flow into the bloodstream at the sub-clavial veins, just
under our necks.
Along
the course of the lymphatic vessels are situated the lymph nodes (lymph glands).
These
nodes are bean-shaped organs containing large numbers of leukocytes. All the
lymph being returned along the lymphatics to the bloodstream must pass through
several of these nodes, which filter out infectious and toxic material and
destroy it.
The
nodes serve as a center for the production of phagocytes, which engulf bacteria
and poisonous substances. During the course of any infection, the nodes become
enlarged because of the large number of phagocytes being produced; these nodes
are often painful and inflamed.
The
swollen glands most often observed are located on the neck, in the armpit, and
in the groin. Certain
malignant tumors tend to “travel” along the lymphatics and sometimes all of
the suspected nodes are removed surgically.
In
addition to the lymph nodes, several organs, are included in the lymphatic
system.
The largest and most important of these organs is the spleen.
Related links & exercises!
Look at the links below, not all but a few and then complete the puzzles below!!
Test your knowledge of this page!
Click here for the tour of the Nervous System