AP BIOLOGY

Detailed explanation-1: -Lymph nodes: Lymph nodes are bean-shaped glands that monitor and cleanse the lymph as it filters through them. The nodes filter out the damaged cells and cancer cells. These lymph nodes also store lymphocytes and other immune system cells that attack and destroy bacteria and other harmful substances in the fluid.

Detailed explanation-2: -Those germs are filtered out in the lymph nodes, small clumps of tissue along the network of lymph vessels. Inside the lymph nodes, lymphocytes called T-cells and B-cells help the body fight infection.

Detailed explanation-3: -Antigens and dendritic cells (DCs) reach the draining lymph node through afferent lymphatic vessels; they must then enter the lymph node and migrate deep into it to activate T cells. Lymph nodes are enclosed in a collagen-rich capsule, which is underlined with lymphatic endothelial cells forming the subcapsular sinus.

Detailed explanation-4: -Bacteria and debris are actively removed from the lymph by macrophages in the sinuses of lymph nodes. Macrophages are phagocytic cells that engulf bacteria and debris.

Detailed explanation-5: -Lymph nodes function to remove debris and pathogens from the lymph, and are thus sometimes referred to as the “filters of the lymph” (see Figure 14.6). Any bacteria that infect the interstitial fluid are taken up by the lymphatic capillaries and transported to a regional lymph node.