Blood vessels join a lymph node through the indented region of the lymph node, called the hilum. Lymph nodes vary in size and shape, but are usually less than 2.5 centimeters long and somewhat bean-shaped (Figure 2 and 3). The site of the swollen lymph nodes may help identify the underlying cause. You may be more likely to notice swelling in certain areas, such as in the lymph nodes in your neck, behind your ears, under your chin, in your armpits and in your groin. Figure 1 shows the major locations of lymph nodes. Lymph nodes are generally in groups or chains along the paths of the larger lymphatic vessels throughout the body and each group drains a specific area of your body, but are absent in the central nervous system. The spaces within a node, called lymphatic sinuses, provide a complex network of chambers and channels through which lymph circulates. Masses of B lymphocytes and macrophages in the cortex are contained within lymphatic nodules, also called lymphatic follicles, the functional units of the lymph node.
Lymph nodes contain large numbers of lymphocytes (B cells and T cells) and macrophages that fight invading microorganisms.
Macrophages in the lymph nodes engulf and destroy foreign substances, damaged cells, and cellular debris. Lymph nodes are important for the proper functioning of the immune system, acting as filters for foreign particles and cancer cells. Lymphocytes attack viruses, bacteria, and other parasitic cells that are brought to the lymph nodes by lymph in the lymphatic vessels.
0 kommentar(er)
