Video Transcript
Which of the following is a
component of the lymphatic system in humans that filters the lymph to identify
microbes? (A) Lymph nodes, (B) kidneys, (C)
blood capillaries, or (D) lymphatic vessels.
This question asks us about the
lymphatic system, which is very important for circulation and immune function in the
body. Let’s review some different
components of the lymphatic system in order to answer this question correctly.
The lymphatic system is composed of
lymphatic vessels, lymph nodes, and organs like the spleen. The lymphatic vessels are
responsible for taking up excess fluid that has not been taken up by the
capillaries, which are the smallest types of blood vessels in the body. Capillaries are leaky, which means
that they allow fluid from within the vessel to bathe over the surrounding tissues,
delivering the oxygen and nutrients it carries. This is called interstitial fluid,
and it fills the space between the cells, the interstitial space. Whilst most of it, about 90
percent, is reabsorbed by the capillaries, the lymphatic vessels are responsible for
absorbing any interstitial fluid that is left over. Once this enters the lymphatic
system, it is considered to be lymph.
The lymphatic vessels eventually
return this fluid to the circulatory system via the subclavian vein, just below the
collarbone. But first it will transport the
lymph through structures called the lymph nodes. These are located throughout the
body. You might have heard of them before
if you’ve ever had swollen lymph nodes in your neck when you were sick. They will swell because the lymph
nodes, which are typically small, bean-shaped structures, will contain white blood
cells called B and T lymphocytes that proliferate, or multiply, in response to
pathogens. Since the lymph may carry these
pathogens from the tissues or the bloodstream, the lymph nodes are able to filter
the lymph to detect them and then to generate an immune response.
The spleen also has a function in
the immune system, though it primarily filters blood. In this way, the spleen filters
blood for pathogens, while the lymph nodes filter lymph.
After reviewing the lymphatic
system and the organs that are involved, let’s return to our question. We now know the correct answer is
(A). The component of the lymphatic
system in humans that filters the lymph to identify microbes is the lymph nodes.
