Download The Lymphatic System - Marshall Middle

(Students: Bolded, italicized, and underlined sections will be on the exam)
The Lymphatic System:
I. Function of the System:
A. To fight germs, which include bacteria, viruses, fungi, and parasites. It is also
important for the distribution of fluids and nutrients in the body, because it
drains excess fluids, fats, and proteins so that tissues do not swell up.
II. The Main Parts of the System: 1. Lymph 2. Lymphatic Vessels 3. Lymph Nodes
A. Lymph: Lymph is essentially plasma with white blood cells that ‘seeps’ outside
of the capillaries of the circulatory system. Lymph:
• is a milky body fluid that contains a type of white blood cells called
lymphocytes (that fight agents of infection, including bacteria and viruses),
along with proteins and fats.
• seeps outside the capillary blood vessels in spaces of body tissues and is stored
in the lymphatic system to flow back into the bloodstream.
• carries away wastes and invading bacteria from the body’s cells.
• moves by random muscular movement of the body.
B. Lymphatic Vessels: Lymphatic Vessels are tubes that collect lymph from the
body. Through these vessels, lymph returns to the bloodstream.
C. Lymph Nodes: Lymph Nodes are enlarged areas of lymphatic vessels. Facts
about lymph nodes::
• They act as barriers to infection by filtering out and destroying toxins and
germs from the lymph before it returns to the bloodstream.
• They produce white blood cells which kill organisms that cause disease.
• They produce antibodies which help the body to fight invading organisms
should they return to the body. Antibodies are protein molecules which
recognize specific chemical structures on the surface of invading organisms.
• There are more than 100 tiny lymph nodes throughout the body. These are
mainly in the neck, groin and armpits, but are scattered all along the lymph
vessels.
• The largest body of lymphoid tissue in the human body is the spleen.
D. Other important parts and information:
Two very large areas are of significance in this system: the right lymphatic duct
which drains lymph fluid from the upper right quarter of the body above the
diaphragm and down the midline, and the thoracic duct, a structure roughly
sixteen inches long located in the mediastinum of the pleural cavity which drains
the rest of the body. It is through the actions of this system including the spleen,
the thymus, lymph nodes and lymph ducts that our body is able to fight infection
and to ward off invasion from foreign invaders.
Lymphatic Vessels/Nodes:
Lymph:
Tonsils:
III. Interaction with Other Systems:
The lymphatic system interacts with every system, since it protects every cell in
every organ system from harmful organisms. Also, it helps to regulate fluid levels
throughout the body. Some examples of systems that directly interact with the
system include:
• The Circulatory System/Immune System: Along with the white blood cells in
the blood, the lymphatic system makes up the immune capability of the
body that fights infection (known as the body’s Immune System). Also,
blood absorbs and contains the lymphatic fluid when it is not flowing in the
lymphatic vessels or body tissue.
• The Digestive System: Fats are absorbed from the small intestines by the lymph
in the bloodstream.
• The Urinary System: Blood, which has the wastes from the lymphatic system, is
filtered by the kidneys.
• IV. Some Diseases and Disorders:
• Hodgkin’s Disease, Lymphoma, or Pseudoleukemia: Enlargement of the
lymphatic glands and outer adenoid tissues, with diminution of red
corpuscles and hemoglobin. Cervical glands usually first involved.!
Symptoms include weakness, anorexia, loss of appetite, and spleen
enlargement.
• Leukocythemia, or Leukemia: Abnormal increase in. the number of white blood
cells, which may start ‘attacking’ healthy cells in the body. Symptoms include
enlargement of the spleen, liver, and lymphatic glands, weakness, diarrhea,
etc... This is more common in men than in women.
V. Other Facts:
• A CBC (Complete Blood Count) test prescribed by a doctor, reveals the number
of white and red blood cells you have. A large number of white blood cells
may indicate an infection, whereas a low number or red blood cells may
indicate that the bone marrow is not working properly.
• Swollen tonsils/lymph nodes in your lower jaw indicate a build up of white
blood cells to fight infection. This is why the doctor ‘feels’ your neck area
for swelling and looks inside of your throat during ‘check ups’.