In the lymphatic system, what structure is primarily responsible for filtering out impurities from lymph?

• A. Lymph nodes
• B. Spleen
• C. Thymus
• D. Bone marrow

Answer: (A)

Verified step by step guidance

1. Understand the role of the lymphatic system: The lymphatic system is responsible for maintaining fluid balance, absorbing fats from the digestive system, and defending the body against pathogens. It achieves this by circulating lymph, a fluid containing white blood cells, throughout the body.
2. Identify the function of lymph nodes: Lymph nodes are small, bean-shaped structures located along the lymphatic vessels. Their primary role is to filter lymph, trapping impurities such as bacteria, viruses, and other foreign particles. They also house immune cells like lymphocytes and macrophages, which help destroy these pathogens.
3. Differentiate the other structures: The spleen filters blood, not lymph, and removes old or damaged red blood cells. The thymus is involved in the maturation of T-cells (a type of white blood cell), and bone marrow is responsible for producing blood cells, including immune cells.
4. Match the function to the structure: Since the question asks for the structure that filters impurities from lymph, and lymph nodes are specifically designed for this purpose, they are the correct answer.
5. Review the options: Confirm that 'Lymph nodes' is the correct choice based on their role in filtering lymph, while the spleen, thymus, and bone marrow have distinct but different functions in the immune and circulatory systems.