Lymphatic system is part of the immune system
- maintains fluid balance and plays a role in absorbing fats and fat-soluble nutrients
- involves an extensive network of vessels that passes through almost all our tissues to allow for the movement of a fluid called lymph
- lymph circulates through the body in a similar way to blood
How do you keep the lymph system healthy?
- Regular exercise
can help to reduce the amount of tissue edema and swelling that the veins and lymph system need to clear.
- Treat lymph system damage early. If you have swelling in an arm or leg from previous injury or cancer treatment, make sure you get treatment early. Reducing the length of time that the lymph system is over-taxed may decrease the long term damage. Kind of like a hernia – you should get it fixed sooner rather than later or it will just expand and get worse.
- Avoid tight fitting clothes. If you have lymphatic issues, compressing the area with tight clothing will only make things worse.
- Physical therapy. Some physical therapists (PTs) specialize in treating lymphedema. They have developed excellent massage techniques that can help to “milk” the lymph back to the blood circulation (called manual lymph drainage). They can also provide special wraps to reduce arm and leg swelling.
Lymphatic filariasis is a parasitic disease caused by three species of microscopic, thread-like worms. The adult worms only live in the human lymph system. The lymph system maintains the body’s fluid balance and fights infections. … People with theworms in their blood can give the infection to others through mosquitoes.
The filarial parasites specifically target the lymphatics and impair lymph flow, which is critical for the normal functions of the lymphatic system
Note: Women should not wear tight fitting clothes to allow the lymph to function and clean the blood.
The lymph is moved through the body in its own vessels making a one-way journey from the interstitial spaces to the subclavian veins at the base of the neck.
- Since the lymphatic system does not have a heart to pump it, its upward movement depends on the motions of the muscle and joint pumps.
- As it moves upward toward the neck the lymph passes through lymph nodes which filter it to remove debris and pathogens.
- The cleansed lymph continues to travel in only one direction, which is upward toward the neck.
- At the base of the neck, the cleansed lymph flows into the subclavian veins on either side of the neck.
What can go wrong with the lymphatic system?
- Mechanical damage can disrupt the flow of lymph fluid, causing fluid back up and swelling.
The lymph vessels are very delicate (almost like spider webs), and their walls are not as tough as arteries or veins. They are therefore quite prone to injury by mechanical and compressive forces. The most common causes of lymphatic system injury are surgery, radiation, and trauma. Luckily the lymphatic system is a complex web that can usually find flow work-arounds. However, if there is extensive damage in a specific area, it can be overwhelming and result in swelling to the nearby limb (for example) previously served by that part of the system.
- Cancer can plug up the system or cancer treatment can damage the lymphatics.
When white blood cells divide out of control and become cancerous, it makes sense that they can damage the circulatory lymph system where they live. Lymphoma is a cancer of the lymph system that directly damages it. Sometimes cancer spreads through the lymph system and travels to other parts of the body. When cancer gets into the lymph nodes, physicians sometimes have to cut those nodes out (lymph node dissections are common in breast cancer treatment, for example) or use radiation to burn the cancer. This can lead to chronic swelling issues in the arms or legs, known as lymphedema.
- Parasites can block the lymphatic system.
As discussed earlier, certain parasitic worms have an affinity for the lymph system and although they can be killed with medicines, the damage they do to the lymph vessels and nodes may be permanent.
There are about 600 lymph nodes in the body. These nodes swell in response to infection, due to a build-up of lymph fluid, bacteria, or other organisms and immune system cells.
A person with a throat infection, for example, may feel that their “glands” are swollen. Swollen glands can be felt especially under the jaw, in the armpits, or in the groin area. These are, in fact, not glands but lymph nodes.
They should see a doctor if swelling does not go away, if nodes are hard or rubbery and difficult to move, if there is a fever, unexplained weight-loss, or difficulty breathing or swallowing.
Fast facts about the lymphatic system
- The lymphatic system plays a key role in the immune system, fluid balance, and absorption of fats and fat-soluble nutrients.
- As lymph vessels drain fluid from body tissues, this enables foreign material to be delivered to the lymph nodes for assessment by immune system cells.
- The lymph nodes swell in response to infection, due to a build-up of lymph fluid, bacteria, or other organisms and immune system cells.
- Lymph nodes can also become infected, in a condition known as lymphadenitis.
- If lymph nodes remain swollen, if they are hard and rubbery, and if there are other symptoms, you should see a doctor.
Lymph nodes, or “glands” may swell as the body responds to a threat.
The lymphatic system has three main functions:
- It maintains the balance of fluid between the blood and tissues, known as fluid homeostasis.
- It forms part of the body’s immune system and helps defend against bacteria and other intruders.
- It facilitates absorption of fats and fat-soluble nutrients in the digestive system.
The system has special small vessels called lacteals. These enable it to absorb fats and fat-soluble nutrients from the gut.
They work with the blood capillaries in the folded surface membrane of the small intestine. The blood capillaries absorb other nutrients directly into the bloodstream.
The lymphatic system consists of lymph vessels, ducts, nodes, and other tissues.
Around 2 liters of fluid leak from the cardiovascular system into body tissues every day. The lymphatic system is a network of vessels that collect these fluids, or lymph. Lymph is a clear fluid that is derived from blood plasma.
The lymph vessels form a network of branches that reach most of the body’s tissues. They work in a similar way to the blood vessels. The lymph vessels work with the veins to return fluid from the tissues.
Unlike blood, the lymphatic fluid is not pumped but squeezed through the vessels when we use our muscles. The properties of the lymph vessel walls and the valves help control the movement of lymph. However, like veins, lymphatic vessels have valves inside them to stop fluid from flowing back in the wrong direction.
Lymph is drained progressively towards larger vessels until it reaches the two main channels, the lymphatic ducts in our trunk. From there, the filtered lymph fluid returns to the blood in the veins.
The vessels branch through junctions called lymph nodes. These are often referred to as glands, but they are not true glands as they do not form part of the endocrine system.
In the lymph nodes, immune cells assess for foreign material, such as bacteria, viruses, or fungus.
Lymph nodes are not the only lymphatic tissues in the body. The tonsils, spleen, and thymus gland are also lymphatic tissues.
What do the tonsils do?
In the back of the mouth, there are tonsils. These produce lymphocytes, a type of white blood cell, and antibodies.
They have a strategic position, hanging down from a ring forming the junction between the mouth and pharynx. This enables them to protect against inhaled and swallowed foreign bodies. The tonsils are the tissues affected by tonsillitis.
What is the spleen?
The spleen is not connected to the lymphatic system in the same way as lymph nodes, but it is lymphoid tissue. This means it plays a role in the production of white blood cells that form part of the immune system.
Its other major role is to filter the blood to remove microbes and old and damaged red blood cells and platelets.
The thymus gland
The thymus gland is a lymphatic organ and an endocrine gland that is found just behind the sternum. It secretes hormones and is crucial in the production, maturation, and differentiation of immune T cells.
It is active in developing the immune system from before birth and through childhood.
The bone marrow
Bone marrow is not lymphatic tissue, but it can be considered part of the lymphatic system because it is here that the B cell lymphocytes of the immune system mature.
Liver of a fetus
During gestation, the liver of a fetus is regarded as part of the lymphatic system as it plays a role in lymphocyte development.
Below is a 3-D model of the lymphatic system, which is fully interactive.
Explore the model using your mouse pad or touchscreen to understand more about the lymphatic system.
The lymph system has three main functions.
The lymphatic system helps maintain fluid balance. It returns excess fluid and proteins from the tissues that cannot be returned through the blood vessels.
The fluid is found in tissue spaces and cavities, in the tiny spaces surrounding cells, known as the interstitial spaces. These are reached by the smallest blood and lymph capillaries.
Around 90 percent of the plasma that reaches tissues from the arterial blood capillaries is returned by the venous capillaries and back along veins. The remaining 10 percent is drained back by the lymphatics.
Each day, around 2-3 liters is returned. This fluid includes proteins that are too large to be transported via the blood vessels.
Loss of the lymphatic system would be fatal within a day. Without the lymphatic system draining excess fluid, our tissues would swell, blood volume would be lost and pressure would increase.
Most of the fats absorbed from the gastrointestinal tract are taken up in a part of the gut membrane in the small intestine that is specially adapted by the lymphatic system.
The lymphatic system has tiny lacteals in this part of the intestine that form part of the villi. These finger-like protruding structures are produced by the tiny folds in the absorptive surface of the gut.
Lacteals absorb fats and fat-soluble vitamins to form a milky white fluid called chyle.
This fluid contains lymph and emulsified fats, or free fatty acids. It delivers nutrients indirectly when it reaches the venous blood circulation. Blood capillaries take up other nutrients directly.
The immune system
The lymphatic system produces white blood cells, or lymphocytes that are crucial in fending off infections.
The third function is to defend the body against unwanted organisms. Without it, we would die very soon from an infection.
Our bodies are constantly exposed to potentially hazardous micro-organisms, such as infections.
The body’s first line of defense involves:
- physical barriers, such as the skin
- toxic barriers, such as the acidic contents of the stomach
- “friendly” bacteria in the body
However, pathogens often do succeed in entering the body despite these defenses. In this case, the lymphatic system enables our immune system to respond appropriately.
If the immune system is not able to fight off these micro-organisms, or pathogens, they can be harmful and even fatal.
A number of different immune cells and special molecules work together to fight off the unwanted pathogens.
How does the lymphatic system fight infection?
The lymphatic system produces white blood cells, known as lymphocytes. There are two types of lymphocyte, T cells and B cells. They both travel through the lymphatic system.
As they reach the lymph nodes, they are filtered and become activated by contact with viruses, bacteria, foreign particles, and so on in the lymph fluid. From this stage, the pathogens, or invaders, are known as antigens.
As the lymphocytes become activated, they form antibodies and start to defend the body. They can also produce antibodies from memory if they have already encountered the specific pathogen in the past.
Collections of lymph nodes are concentrated in the neck, armpits, and groin. We become aware of these on one or both sides of the neck when we develop so-called “swollen glands” in response to an illness.
It is in the lymph nodes that the lymphocytes first encounter the pathogens, communicate with each other, and set off their defensive response.
Activated lymphocytes then pass further up the lymphatic system so that they can reach the bloodstream. Now, they are equipped to spread the immune response throughout the body, through the blood circulation.
The lymphatic system and the action of lymphocytes, of which the body has trillions, form part of what immunologists call the “adaptive immune response.” These are highly specific and long-lasting responses to particular pathogens.
The lymphatic system can stop working properly if nodes, ducts, vessels, or lymph tissues become blocked, infected, inflamed, or cancerous.
Cancer that starts in the lymphatic system is known as lymphoma. It is the most serious lymphatic disease.
Hodgkin lymphoma affects a specific type of white blood cell known as Reed-Sternberg cells. Non-Hodgkin lymphoma refers to types that do not involve these cells.
Cancer that affects the lymphatic system is usually a secondary cancer. This means it has spread from a primary tumor, such as the breast, to nearby or regional lymph nodes.
- Damage disturbs the flow. When lymphatic tissues or lymph nodes have been damaged, destroyed or removed, lymph cannot drain normally from the affected area. When this happens excess lymph accumulates and results in the swelling that is characteristic of lymphedema.
- Drainage areas. The treatment of lymphedema is based on the natural structures and the flow of lymph. The affected drainage area determines the pattern of the manual lymph drainage (MLD) and for self-massage. Although lymph does not normally cross from one area to another, MLD stimulates the flow from one area to another. It also encourages the formation of new lymph drainage pathways.
- MLD treatment and self-massage begin by stimulating the area near the terminus and the larger lymphatic vessels. This stimulates the flow of lymph that is already in the system and frees space for the flow of the lymph that is going to enter the capillaries during the treatment.
- MLD treatment continues as a gentle massage technique to stimulate the movement of the excess lymph in affected tissues. The rhythmic, light strokes of MLD provide just the right pressure to encourage this excess lymph to flow into the lymph capillaries.
- The compression garments, aids, and/or bandages that are worn between treatments help control swelling by providing pressure that is needed to encourage the flow of lymph into the capillaries.
- Exercise is important in the treatment of lymphedema because the movements of the muscles stimulate the flow of the lymph into the capillaries. Wearing a compression garment during exercise also provides resistance to further stimulate this flow.
- Self-massage or simplified lympatic drainage, as prescribed by your therapist, is another way in which lymph is encouraged to flow into the capillaries. Each self-massage session begins at the terminus with strokes to stimulate the flow of lymph that is already in the system. This is followed by specialized strokes that encourage the flow of lymph into the capillaries and then upward to the terminus.
Other lymphatic system organs
The lymphatic system includes other organs, such as the spleen, thymus, tonsils and adenoids.
The spleen is under your ribs, on the left side of your body. It has 2 main different types of tissue, red pulp and white pulp.
The red pulp filters worn out and damaged red blood cells from the blood and recycles them.
The white pulp contains many B lymphocytes and T lymphocytes. These are white blood cells that are very important for fighting infection. As blood passes through the spleen, these blood cells pick up on any sign of infection or illness and begin to fight it.
The thymus is a small gland under your breast bone. It helps to produce white blood cells to fight infection. It is usually most active in teenagers and shrinks in adulthood.
The tonsils and adenoids
The tonsils are 2 glands in the back of your throat.
The adenoids are glands at the back of your nose, where it meets the back of your throat. The adenoids are also called the nasopharyngeal tonsils.
The tonsils and adenoids help to protect the entrance to the digestive system and the lungs from bacteria and viruses.