• Many different organs and systems work
together in an effort to keep us alive and healthy.
• In this ongoing struggle, the lymphatic system
plays a central role.
• The lymphatic system is an extensive drainage
network that helps keep bodily fluid levels in
balance, defends the body against infections,
and assists in tissue repairs.
• The production, maintenance and distribution of
– to defend the body against disease by producing
– The lymphocytes, protect the body against antigens
(viruses, bacteria, etc.) that invade the body.
– Lymphocytes are produced and stored within
lymphoid organs, such as the spleen, thymus and
• The return of fluid and solutes from the
peripheral tissues of the blood.
– to collect and return interstitial fluid, including
plasma protein to the blood,
and thus help maintain fluid balance.
– The return of fluids through the lymphatic
system maintains normal blood volume.
– The flow is ~3.6 liters per day and a break in a
major lymphatic vessel can cause a rapid and
potentially fatal decline in blood volume.
• The distribution of hormones, nutrients
and waste products from their tissues to
the general circulation.
–to absorb lipids from the intestine and
transport them to the blood.
–Substances that are unable to enter the
blood stream directly can do so via the
• 3 components
• 1. Vessels-
– A network of lymphatic vessels that begins in the peripheral
tissues and connects to the venous system.
• 2. Fluid
– Called Lymph (clear and watery), flows through the lymphatic
– Lymph Fluid contains:
• Fluid from the intestines (chyme), which contains proteins and fats.
• Red blood cells
• White blood cells, especially lymphocytes, the cells that attack
bacteria in the blood
• 3. Lymphoid organs-
– Lymphoid organs are connected to the lymphatic vessels and
contain large numbers of lymphocytes. (Ex. Lymph nodes,
spleen and thymus).
• Carry lymph from the peripheral tissues to the
venous system in all parts of the body except the
CNS (central nervous system).
• The smallest vessels are called lymphatic
capillaries. These capillaries carry lymph to the
larger lymphatic vessels.
• The lymphatic vessels ultimately empty into two
large collecting ducts: thoracic duct and right
– Lymph organs include the bone marrow, lymph
nodes, spleen, and thymus.
– Human lymph nodes, called lymph glands and “swollen
glands,” are bean-shaped and range in size from a few
millimeters to about 1-2 cm in their normal state.
– They may become enlarged due to a tumor or
– White blood cells are located within honeycomb
structures of the lymph nodes.
– Spleen- The spleen, which is located in the upper left
part of the abdomen under the ribcage, works as part
of the lymphatic system to protect the body.
– It clears worn out red blood cells and other foreign
bodies from the bloodstream to help fight off infection.
• Tonsil—The tonsils are areas of lymphoid
tissue on either side of the throat.
• An infection of the tonsils is called
• Thymus- an organ located in the upper
anterior portion of the chest cavity just
behind the sternum.
• Hormones produced by this organ
stimulate the production of certain
• Through the hormones it produces, the thyroid
gland influences almost all of the metabolic
processes in your body.
• Thyroid disorders can range from a small,
harmless goiter (enlarged gland) that needs no
treatment to life-threatening cancer.
• The most common thyroid problems involve
abnormal production of thyroid hormones.
• Too much of these vital body chemicals results in
a condition known as hyperthyroidism.
• Insufficient hormone production leads to
• All types of hyperthyroidism are due to an
overproduction of thyroid hormones, but the
condition can occur in several different ways.
• By contrast, stems from an underproduction of
• For your body to have the energy it needs, it
requires certain amounts of thyroid hormones, a
drop in hormone production leads to lower