Most people know that their lymph nodes can swell when they have a throat infection, but why does this happen and what else is there to know about the body’s lymphatic system?
The lymphatic system is similar in many aspects to the circulatory system of the blood, since it implies a wide network of vessels that cross all our tissues to allow the movement of a liquid called lymph.
This fluid drains through these lymphatic vessels in a way that is very similar to pumping the blood along the veins to the heart.
Interesting facts about the lymphatic system
Here are some key points about the lymphatic system.
The lymphatic system has three main functions: it is part of our immune system, maintains fluid balance and is essential for the absorption of fats and fat-soluble nutrients.
The lymphatic vessels drain the fluid from virtually all of our tissues to control the fluid balance and to carry the foreign material to the lymph nodes for evaluation by the cells of the immune system.
The lymph nodes swell in response to infection due to an accumulation of lymphatic fluid, bacteria or other organisms and cells of the immune system.
Lymph nodes can also become inflamed due to direct infection and, in rare cases, cancer or other diseases or conditions.
The lymph nodes are responsible for filtering the lymph and providing part of the adaptive immune response to new pathogens, the part of our immunity that has a long “memory”.
Lymphatic system disorders include lymphedema, a form of swelling that occurs when the lymph has not drained through the lymphatic vessels.
Inflamed lymph nodes may indicate a response to a foreign material, such as a nearby infection. This process is known as reactive lymphadenopathy.
The lymph nodes can also become infected by themselves, a condition known as lymphadenitis.
If the swollen lymph nodes do not return to their normal size, they become hard or rubbery and difficult to move, they are accompanied by fever, unexplained weight loss, difficulty breathing or swallowing, a medical check-up is needed.
The lymphatic system can become dysfunctional if lymph nodes, ducts, vessels or lymphatic tissues become blocked, infected, inflamed or cancerous.
This can lead to a combination of two or three of the following general characteristics of lymphatic disorders:
When a lymphatic disorder involves obstruction, lymphatic fluid builds up in the tissues, a condition known as lymphedema (also spelled lymphedema).
The infection can lead to enlargement of the lymph nodes.
Cancer – the less common but more serious lymphatic disease, lymphoma is usually secondary and arises when the cancer spreads from a primary tumor (such as in the breast) to nearby or regional lymph nodes. It is rare for a cancer to start in the lymphatic system itself (a primary cancer).
What are inflamed lymph nodes?
Inflamed glands – for example, in the neck during a throat infection – are enlarged lymph nodes. The lymph nodes can swell for two common reasons:
Reaction to an infection (reactive lymphadenopathy) – when the lymph nodes react to foreign material presented to the immune cells through the lymph drained from infected tissue.
Direct infection of the lymph nodes that lead to inflammation (lymphadenitis) – usually associated with certain infections that require rapid antibiotic treatment.
It is best to seek medical advice in case of doubt or if the lymph nodes remain swollen for more than a week or two.
You should also seek medical advice if a swollen lymph node feels hard or fixed in place, or if the swelling is accompanied by fever, night sweats or unexplained weight loss.
The inflamed lymph nodes can be symptomatic of numerous possible conditions. Glandular fever is a more lasting cause of swelling – this viral infection is also known as infectious mononucleosis.
Children are more likely to have swollen lymph nodes because their immune systems are developing responses to infectious microbes.
Tonsillitis, for example, is more common in children. This condition occurs when the lymph nodes in the back of the mouth are fighting infection – usually viral, but less commonly a bacterial infection.
Pharyngitis is a type of bacterial infection, commonly called “strep throat,” caused by group A streptococcus bacteria.
It is not surprising that many infectious diseases produce symptoms associated with the lymphatic system.
This, because the lymphatic system is involved with the production of lymphocytes that fight infectious diseases, and the lymphatic system filters the blood and lymph to eliminate the microorganisms.
Lymphadenitis (inflammation of the lymph nodes), makes them become enlarged and sensitive. It is an indication that the microorganisms are being trapped and destroyed inside the lymph nodes.
Sometimes the lymphatic vessels become inflamed to produce lymphangitis. This often results in visible red streaks on the skin that extend away from the site of infection.
If the microorganisms pass through the lymphatics and lymph nodes to reach the blood, it can result in septicemia or blood poisoning.
Bubonic plague and elephantiasis are diseases of the lymphatic system.
Fortunately, there are relatively few cases today. The bubonic plague is caused by bacteria that are transferred to humans by the bite of the rat flea.
The bacteria are located in the lymph nodes, causing the lymph nodes to enlarge. The term “bubonic” is derived from a Greek word that refers to the groin because the disease often causes the inguinal lymph nodes in the groin to swell.
Without treatment, bacteria enter the blood, multiply and infect tissues throughout the body, causing rapid death in 70 to 90% of those infected.
Elephantiasis is caused by long and thin worms. Adult worms lodge in the lymphatic vessels and cause blockage of the lymphatic flow.
The accumulation of fluid in the interstitial spaces and lymphatic vessels that occurs can cause swelling and permanent enlargement of a limb.
The affected limb supposedly resembles the leg of an elephant, providing the basis for the name of the disease. The descendants of adult worms pass through the lymphatic system in the blood, from which they can be transferred to another human being by mosquitoes.
A lymphoma is a neoplasm (tumor) of lymphatic tissue. Lymphomas are generally divided into two groups: (1) Hodgkin’s disease, and (2) all other lymphomas, which are called non-Hodgkin’s lymphomas.
Typically, lymphomas begin as an enlarged, painless mass of the lymph nodes. The immune system is depressed, and the patient has an increased susceptibility to infections.
Enlargement of the lymph nodes can also compress the surrounding structures and produce complications. Fortunately, drug treatment and radiation is effective for many people suffering from lymphoma.