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Question Video: Recalling the Function of Lymph Nodes in the Lymphatic System Biology

Which of the following is a primary function of lymph nodes? [A] Lymph nodes circulate the lymph back to the tissue it came from. [B] Lymph nodes are responsible for the transport of lymph from tissue to the circulatory system. [C] Lymph nodes are responsible for initiating an immune response to an infection by a pathogen. [D] lymph nodes initiate the conversion of waste material in the lymph into useful substances.

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Video Transcript

Which of the following is a primary function of lymph nodes? (A) Lymph nodes circulate the lymph back to the tissue it came from. (B) Lymph nodes are responsible for the transport of lymph from tissue to the circulatory system. (C) Lymph nodes are responsible for initiating an immune response to an infection by a pathogen. Or (D) lymph nodes initiate the conversion of waste material in the lymph into useful substances.

This question asks us about the primary function of lymph nodes. Let’s take a look at the lymphatic system and the role of lymph nodes to figure out the answer. The lymphatic system plays important roles in the circulatory system and the immune system. In the circulatory system, blood is pumped from the heart to the different tissues of the body through blood vessels. When the blood vessels reach the body tissues, they branch into finer vessels, which are called capillaries. The capillaries form a network around the cells of the tissues, forming a capillary bed.

Fluid containing oxygen and other nutrients is released from the capillaries and into the spaces between the cells. The spaces between the cells are called the interstitial spaces. The cells take up the oxygen and nutrients they need and release their waste products back into the interstitial fluid in these spaces. Most of the interstitial fluid remaining is then taken up by the capillaries and fed back into the bloodstream to be returned to the heart. However, a small volume of fluid remains in the interstitial spaces. The lymphatic system is responsible for collecting this remaining fluid. This occurs in lymphatic capillaries, which then drain back into the circulatory system. Once the fluid is taken up by the lymphatic vessels, it is called lymph.

Lymph contains a lot of water and carries proteins, fats, and other materials. It might also carry pathogens, for example, disease-causing microorganisms or viruses, from the tissues. As the lymph travels through the lymphatic vessels on its way back to the bloodstream, it passes through lymphatic organs called lymph nodes.

Lymph nodes are small bean-shaped structures found in groups all over the body. They contain immune cells called lymphocytes. If the lymph passing through the lymph nodes contains pathogens, the lymphocytes become activated. They generate an immune response to the pathogen, destroying or inactivating it. The lymphocytes then exit the lymph nodes along with the lymph to travel through the bloodstream and attack all other similar pathogens throughout the body.

If we take a look at the options in the question, we can see that option (C) correctly outlines the primary function of lymph nodes in the body. The correct answer is therefore option (C). The lymph nodes are responsible for initiating an immune response to an infection by a pathogen.

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