Lymph must travel through the lymph nodes before it is returned to the bloodstream. The lymph nodes are shaped like the kidneys with a convex surface and a concave surface (also known as the hilum). Lymph enters the lymph nodes at the convex surface and is funneled toward the hilum. This slows the flow of lymph through the lymph node, just like traffic on the highway slows down when lanes are closed. This allows time for lymphocytes (B cells and T cells) and macrophages in the lymph nodes to detect pathogens and clear out bacteria and debris. Sometimes during infection, the lymph nodes become clogged with dying bacteria and immune cells which triggers inflammation. This is most often observed in the cervical lymph nodes (the ones in your neck) and is often referred to as "swollen glands." Keep in mind that this is a misnomer. There are no actual glands in the lymph nodes.