Video Transcript
What are the major components of
the lymphatic system? (A) Lymph, lymphatic cells, and the
heart. (B) Lymph, the lymphatic nervous
system, and lymph nodes. (C) Lymph, lymphatic skin cells,
and lymph nodes. Or (D) lymph, lymph nodes, and
lymphatic vessels.
To answer this question, let’s
review the key facts about the lymphatic system, including its definition.
The lymphatic system is the system
of the body that transports excess fluid and some important substances from the
tissues of body into the vessels of the circulatory system. It also has an important role in
the immune system as it transports white blood cells to fight infection. To carry out its role, it is made
up of a series of organs, tissues, vessels, and nodes. Let’s use this diagram to look at
how it works.
The arterioles and venules are
small branches of the arteries and veins, respectively, which lead to and from
capillary beds. Remember that arteries take blood
away from the heart and veins bring blood back to it. Here, we can see that some blood
leaks out of the capillaries and into the interstitial space, or space surrounding
cells in the body. This will allow for oxygen and
nutrients to be transferred to the cells and for waste products to be taken
away.
The majority of the interstitial
fluid, as it is now called, will be taken back up by the venules. But some will remain in the tissues
then be transferred to the capillaries of the lymphatic system, as illustrated
here. Once the fluid is in the lymphatic
system, it is called lymph.
Let’s now look at another diagram
to see what happens to the lymph in the lymphatic system. The lymph will enter the lymphatic
capillaries at the bottom of the image then travel into the lymphatic vessels. It will then pass through
structures called lymph nodes, which are part of the immune system. And finally it will go through
lymphatic ducts into subclavian veins, from where it will ultimately go to the
heart.
Let’s examine the lymph nodes a
little further. These are bean-shaped glands that
act as filters for damaged cells and cancer cells. They also produce and store special
kinds of white blood cells called B and T lymphocytes, which are important in immune
function. For example, B lymphocytes are the
cells that secrete antibodies. Pathogens in the body will be
trapped and taken to lymph nodes, which will activate the lymphocytes and cause them
to enter the circulatory system to attack pathogens. There are approximately 600 lymph
nodes in your body. Some act on their own, and some
work in connected groups. You may have noticed the ones found
in the neck and armpit due to them being painful when you are ill.
Now that we have reviewed the key
facts about the lymphatic system and its components, let’s return to the
question. We now know that the correct answer
is (D). The major components of the
lymphatic system are the lymph, lymph nodes, and lymphatic vessels.
