The primary substrate filtered by lymph nodes is:

The primary substrate filtered by lymph nodes is:

• A. Lymph
• B. Blood
• C. Urine
• D. Bile

Answer: (A)

Lymph nodes filter lymph. Lymph is the fluid that drains from tissues into the lymphatic vessels and carries immune cells, debris, and potential pathogens. As lymph travels through a node, macrophages and lymphocytes inspect it, phagocytose invaders, and present antigens, helping to trap pathogens before the fluid returns to the bloodstream. This immune surveillance is specific to lymph; blood is filtered by organs like the kidneys and spleen, urine is the filtrate processed by the kidneys, and bile is produced and modified by the liver and stored by the gallbladder. So the primary substrate filtered by lymph nodes is lymph.

Lymph nodes filter lymph. Lymph is the fluid that drains from tissues into the lymphatic vessels and carries immune cells, debris, and potential pathogens. As lymph travels through a node, macrophages and lymphocytes inspect it, phagocytose invaders, and present antigens, helping to trap pathogens before the fluid returns to the bloodstream. This immune surveillance is specific to lymph; blood is filtered by organs like the kidneys and spleen, urine is the filtrate processed by the kidneys, and bile is produced and modified by the liver and stored by the gallbladder. So the primary substrate filtered by lymph nodes is lymph.