What are lymph nodes?

Lymph nodes are the most important immune organs in our body and can effectively resist external viruses. If the body is damaged or inflamed, the lymph nodes will react, causing the lymph nodes to enlarge. This is normal. We often see that children have protruding lymph nodes behind their ears after they have a fever. Let's take a look at what lymph nodes are.

Do you all know what lymph nodes are? It is an immune organ and a very important one. It is an organ unique to mammals and can respond well to the emergence of some viruses. If swollen lymph nodes appear, everyone should pay attention, as there may be some problems with the body.

Lymph nodes are important immune organs in the body. Various injuries and stimulations often cause reactive proliferation of lymphocytes and tissue cells in the lymph nodes, causing lymph node enlargement, which is called reactive lymph node hyperplasia. There are many reasons for this, including bacteria, viruses, poisons, toxic products of metabolism, denatured tissue components and foreign matter, all of which can become antigens or allergens to stimulate lymphatic tissue and cause reactions. The degree of lymph node enlargement varies, sometimes reaching 10 cm. Lymph nodes are part of the lymphatic system. The lymphatic system is a component of the vascular system and is composed of lymphatic vessels at various levels, lymphatic organs and scattered lymphatic tissues. The lymphatic system is filled with colorless and transparent lymph (fluid). When blood flows through arteries to capillaries, some of the liquid substances in it pass through the capillary walls into the tissue spaces, forming tissue fluid. After the tissue fluid exchanges substances with cells, most of it is absorbed into the blood through the venous end of the capillaries, and a small part of the tissue fluid containing water and large molecular substances enters the capillary lymphatic vessels to become lymph. Lymph flows centripetally along the lymphatic vessels at all levels, is filtered by many lymph nodes, and finally flows into the veins. Therefore, the lymphatic system can be regarded as an auxiliary structure of the veins. The lymphatic system not only helps the veins transport body fluids back to the blood circulation, but also transports fats and other large molecules. Lymphatic organs and lymphatic tissues can also reproduce and proliferate lymphocytes, filter lymph fluid, and participate in the immune process. They are an important protective barrier for the human body.

Distribution of lymph

Lymph nodes are distributed throughout the body, and only the more superficial ones can be touched. The neck, submandibular area, supraclavicular fossa, axilla, and groin are easiest to feel. When the lymph nodes are swollen, round, oval or cord-like nodules can be felt under the skin. If you feel swollen lymph nodes under the jaw, it means there is a lesion in the mouth. Such as tonsillitis, periodontitis, etc. When a cluster of spherical bumps appear on the neck, cervical tuberculosis should be considered first.

Superficial lymph nodes of the head and neck

Patients with nasopharyngeal carcinoma can often feel swollen lymph nodes in the neck. Swollen lymph nodes in the armpit often indicate disease in the upper limbs or breasts. Swollen inguinal lymph nodes are a sign of infectious disease in the lower limbs and buttocks. In addition, people are reminded not to ignore the pathological reactions caused by uterine cancer, testicular cancer, and rectal cancer. Enlarged left supraclavicular lymph nodes usually indicate that cancer cells in the abdominal cavity have metastasized along the thoracic duct. Such as liver cancer, stomach cancer, colon cancer, etc. Enlarged right supraclavicular lymph nodes indicate that cancer cells in the chest cavity have metastasized upward along the right lymphatic vessels. Such as lung cancer, esophageal cancer, etc. When suffering from lymphocytic leukemia, lymph nodes throughout the body will become swollen.

Understanding the nature of lymphadenopathy is also important for the diagnosis of the disease. If it is an acute or chronic inflammation, the lymph nodes are soft and movable, have no adhesion to the surrounding tissues and skin, and have a sense of freedom. In the acute phase, there are typical symptoms of redness, swelling, heat and pain. In the early stages of lymph node tuberculosis, there is no adhesion to the skin and surrounding tissues, but the disease may continue to swell as it worsens.

Key Features

The main function is to filter lymph, produce lymphocytes and plasma cells, and participate in the body's immune response. When there is a local infection, bacteria, viruses or cancer cells may invade along the lymphatic vessels, causing local lymph node swelling. If the lymph nodes cannot prevent and eliminate them, the lesions may spread and metastasize along the flow direction of the lymphatic vessels.

⑴ Filtering lymph fluid: After pathogens invade the subcutaneous tissue or mucous membrane, they can easily enter the capillary lymphatic vessels and flow back into the lymph nodes. When lymph flows slowly through the lymph sinuses, macrophages can clear out foreign matter in it. For example, the clearance rate for bacteria can reach 99%, but the clearance rate for viruses and cancer cells is often very low. The clearance rate is often closely related to the nature, virulence, quantity and immune status of the antigen.

⑵ Conduct immune response: After the antigen enters the lymph nodes, macrophages and interdigitating cells can capture and process the antigen, causing the lymphocytes of the corresponding specific receptors to transform. The site of antigen recognition and cell-cell collaboration is at the junction of the superficial cortex and the deep cortex. When a humoral immune response is induced, the number and size of lymph nodules increase, and the number of plasma cells in the medullary cords increases. When a cellular immune response is induced, the paracortical area is significantly enlarged and the output of effector T cells increases. T cells in the lymph nodes account for about 75% of the total number of lymphocytes, B cells account for 25%, and there are very few or no large granular lymphocytes. Cellular immune responses and humoral immune responses in the lymph nodes often occur simultaneously, and which one is dominant depends on the nature of the antigen. There are many nerve endings in the lymph node parenchyma, but they have not yet been found in the lymph nodules. There are a variety of neurotransmitter receptors on the surface of lymphocytes, indicating that the nervous system has a certain regulatory effect on the immune response in the lymph nodes.

Lymph nodes have many functions. Everyone should have an understanding of what lymph nodes are. They play a big role in our body and can enhance our immunity. We should take good care of our bodies. There are really many people with sub-health and many lymphatic diseases. We should have regular physical examinations.