What is the primary function of lymph nodes?

• A. Regulate blood flow
• B. Filter lymph and assist immune responses
• C. Store bile
• D. Break down glucose

Answer: (B)

The primary function of lymph nodes involves filtering lymphatic fluid and assisting immune responses. Lymph nodes act as critical components of the lymphatic system, which plays a pivotal role in the body's immune defense.

As lymph fluid circulates through the body, it collects pathogens, waste products, and other foreign materials. When this lymph enters a lymph node, immune cells, such as lymphocytes and macrophages, examine the fluid for these potential threats. If pathogens are identified, the immune cells can activate and proliferate, launching an immune response to eliminate the infection or foreign material. This filtering process is essential for maintaining the body's health and helps prevent the spread of infections.

In contrast to this function, the other options presented do not relate to the primary purpose of lymph nodes. Regulating blood flow pertains to the function of the cardiovascular system rather than the lymphatic system. Storing bile is a function associated with the liver and gallbladder, and breaking down glucose is involved in metabolic processes primarily facilitated by the liver and other tissues, not lymph nodes. Thus, the correct choice emphasizes the important role lymph nodes play in both filtration and the immune response.