Lymphatic system – structure, functions, diseases. How does the lymphatic system work?

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The lymphatic system is part of the immune system. It also maintains fluid balance and plays a role in the absorption of fats and fat-soluble nutrients. The lymphatic system includes a vast network of vessels that passes through almost all of our tissues, allowing a fluid called lymph to flow through. Lymph circulates through the body in a similar way to blood. There are approximately 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 cells of the immune system. Swollen lymph nodes can be felt especially under the jaw, in the armpits or in the groin area. If the swelling persists, if the knots are hard or rubbery, if you experience fever, unexplained weight loss, or have difficulty breathing or swallowing see your doctor.

Unlike blood, lymph fluid is not pumped, but squeezed through the vessels when we use muscles. The properties of the lymphatic vessel walls and valves help to control the movement of the lymph. However, like veins, lymph vessels contain valves that stop the fluid from flowing back. Lymph is gradually drained towards the larger vessels until it reaches the two main lymphatic channels in our trunk. From there, the filtered lymph fluid returns to the bloodstream through the veins.

The vessels branch through connections called lymph nodes. These are often referred to as glands, but they are not real glands as they are not part of the endocrine system. In the lymph nodes, the immune cells assess the presence of foreign material such as bacteria, viruses, or fungi.

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Lymphatic system and other organs

Lymph nodes aren’t the only lymph tissues in the body. The tonsils, spleen, and thymus are also lymphatic tissues.

Lymphatic system and tonsils

The tonsils are at the back of the mouth. They produce lymphocytes, a type of white blood cell, and antibodies. The tonsils occupy a strategic position, hanging from the ring that creates the connection between the mouth and throat. Thanks to this, they protect against inhalation and swallowing of foreign bodies. The tonsils are tissues that can be affected by tonsillitis.

The lymphatic system and the spleen

The spleen is not connected to the lymphatic system in the same way as lymph nodes, but it is a lymphoid tissue. This means that it plays a role in the production of white blood cells, which are part of the immune system.

Another important role for the spleen is to filter the blood to remove microbes as well as old and damaged red blood cells and platelets.

The lymphatic system and the thymus

The thymus is a lymphatic organ and endocrine gland that is located just behind the breastbone. It secretes hormones and plays a key role in the production, maturation and differentiation of T cells. The thymus actively develops the immune system from birth and throughout childhood.

Lymphatic system and bone marrow

Bone marrow is not a lymphoid tissue, but it can be considered part of the lymphatic system as this is where the immune system’s B cells mature.

Lymphatic system and Peyer’s patches

Composed of lymphatic follicles, these tiny masses of tissue line the walls of the ileum in the small intestine. Lymphoid cells not only identify and destroy germs and other pathogens, but also play a large role in defending against future infections. In fact, more than 50 percent of the cells responsible for producing antibodies come from the gut wall.

The lymphatic system and the appendix

The appendix contains lymph tissue that kills germs. Although often viewed as a redundant organ in adults, the appendix plays an important role in children, helping the immune system fight the disease.

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The lymphatic system and the fetal liver

During pregnancy, the fetal liver is considered part of the lymphatic system as it plays a role in the development of lymphocytes.

Functions of the lymphatic system – fluid balance

The lymphatic system helps to maintain fluid balance. It returns excess fluids and proteins from tissues that cannot be returned by blood vessels. Fluid resides in tissue spaces and cavities, in the tiny spaces that surround cells called interstitial spaces. The smallest blood and lymph vessels reach them.

About 90 percent of the plasma that reaches the tissues from the arterial blood capillaries is returned through the venous capillaries and back along the veins. The remaining 10 percent is drained back through the lymphatic system. About 2-3 liters are returned each day. This fluid contains proteins that are too large to be transported through the blood vessels. Loss of the lymphatic system would be fatal within one day. Without a lymphatic system to drain excess fluid, our tissues would swell, blood volume would be lost, and pressure would increase.

Functions of the lymphatic system – fat absorption

Most of the fats absorbed from the gastrointestinal tract are absorbed in the part of the intestinal membrane in the small intestine that is specially adapted by the lymphatic system.

The lymphatic system contains tiny milk vessels in this part of the intestine that form part of the villi. These protruding finger-like structures are formed by tiny folds on the absorbent surface of the intestine. The milk vessels absorb fat-soluble vitamins and fat, forming a milky white fluid called milk, or digestive lymph. This fluid contains lymph and emulsified fats, i.e. free fatty acids. It provides nutrients indirectly when it reaches the venous circulation. The capillaries take up other nutrients directly.

See also: Hard to digest fats

Functions of the lymphatic system – the immune system

The third function is to defend the body against unwanted organisms. Without it, we would die of infection very quickly. Our bodies are constantly exposed to potentially dangerous microorganisms.

The body’s first line of defense includes:

1. physical barriers such as skin;
2. toxic barriers such as acid stomach contents;
3. “Friendly” bacteria in the body.

However, pathogens often manage to enter the body despite these defense mechanisms. In this case, the lymphatic system enables our immune system to react appropriately. If the immune system is unable to fight off these microorganisms or pathogens, they can be harmful and even fatal.

A range of different immune cells and special molecules work together to fight unwanted pathogens.

Also check: Intestinal microflora – signals that it is disturbed

When the lymphocytes are activated, they form antibodies and begin to defend the body. They can also make antibodies from memory if they have had contact with a specific pathogen in the past. The collection of lymph nodes is concentrated in the neck, armpits, and groin. They make themselves felt on one or both sides of the neck when we develop so-called lymphadenopathy in response to illness. It is in the lymph nodes that lymphocytes first meet pathogens, communicate with each other, and trigger a defensive response.

The activated lymphocytes then travel further up the lymphatic system to reach the bloodstream. They are now adapted to spread the immune response throughout the body through blood circulation.

The lymphatic system and the action of the trillions of lymphocytes are part of what immunologists call “specific immune responses.” These are highly specific and long-lasting responses to specific pathogens.

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Lymphatic system – the most common diseases

The lymphatic system may stop working properly if lymph nodes, vessels, or tissues become blocked, infected, inflamed, or cancerous.

Diseases of the lymphatic system – cancer

The cancer of the lymphatic system can be primary or secondary. Lymphoma refers to cancer that originates in the lymphoid tissue. Lymphoid leukemias and lymphomas are now considered cancers of the same type of cell line.

When it comes to lymphoma, it is either Hodgkin’s lymphoma or non-Hodgkin’s lymphoma. Hodgkin’s lymphoma is characterized by a particular type of cell called a Reed-Sternberg cell, visible under a microscope. It is associated with past Epstein-Barr virus infection and generally causes painless lymphadenopathy. Chemotherapy usually involves ABVD and may also include radiation therapy. In turn, non-Hodgkin’s lymphoma is a cancer characterized by increased proliferation of B cells or T cells, and usually occurs in an older age group than Hodgkin’s lymphoma. It is treated depending on whether it has a high or low grade, and has a worse prognosis than Hodgkin’s lymphoma.

Malignant lymphangioma (lat. lyphangiosarcoma) is a malignant neoplasm of soft tissues, while soft tissue sarcoma (STS) is a benign neoplasm often associated with Turner syndrome. Lymphangioleiomyomatosis (lymphangioma) is a benign tumor of the smooth muscle of the lymphatic system that occurs in the lungs.

Lymphocytic leukemia is another form of cancer in which the host is devoid of various lymphatic cells.

See also: The insidious disease of young women

Diseases of the lymphatic system – lymphadenopathy

Lymphadenopathy (lat. lymphadenopathia) refers to one or more enlarged lymph nodes. In general, small groups or singly enlarged lymph nodes are reactive in response to infection or inflammation. This is called local lymphadenopathy. When multiple lymph nodes in different areas of the body are involved, this is called systemic lymphadenopathy.

Lymphadenopathy can be caused by infections such as infectious mononucleosis, tuberculosis and HIV, connective tissue diseases such as systemic lupus erythematosus and rheumatoid arthritis, and cancer, including both of the lymph node tissue cancers discussed earlier, and cell metastasis cancer from other parts of the system. body that arrived through the lymphatic system.

Diseases of the lymphatic system – lymphoedema

Lymphoedema is swelling caused by lymph build-up and can occur when the lymphatic system is damaged or has an abnormality. It usually affects the extremities, although the face, neck and abdomen can also be affected. In its extreme state, called elephantiasis, the swelling progresses to the point where the skin becomes thick and looks similar to the skin of an elephant’s limbs.

The causes are unknown in most cases, but sometimes there is a history of serious infections, usually from a parasitic disease such as lymphatic filariasis.

Lymphedema can also occur after surgical removal of the lymph nodes under the arm (causing the arm to swell due to poor lymph drainage) or the groin (causing the leg to be swollen). Conventional treatment consists of lymphatic drainage and the use of compression garments.

Reaction to infection – Lymph nodes respond when foreign material is presented to cells of the immune system by the lymph which is drained from infected tissue.

Direct infection of the lymph nodes: Nodes can become infected and become inflamed from certain infections that require prompt treatment with antibiotics. We are talking then about inflammation of the lymph nodes.

Most people who have swollen lymph nodes during a cold or flu don’t need to see a doctor.

However, you should seek medical advice if:

1. lymph nodes remain swollen for more than 1 to 2 weeks;
2. swollen lymph node is hard or immobilized;
3. the swelling is accompanied by fever, night sweats or unexplained weight loss.

Swollen lymph nodes can be a symptom of many diseases

1. Glandular fever: Also known as infectious mononucleosis or monocytic angina, this is a viral infection that can cause prolonged swelling, sore throat and fatigue.
2. Inflammation of tonsils: occurs more often in children than in adults. It occurs when the lymph nodes at the back of the mouth are fighting an infection, usually viral but sometimes bacterial.
3. Acute pharyngitis: This bacterial infection. It is caused by group A streptococcus bacteria and can cause the lymph nodes to swell.

Children are more prone to swollen lymph nodes because their immune system continues to develop responses to infectious microbes.

See also: Throat infections in little ones

Lymphatic system – the spread of cancer

In the clinical world, the process of cancer spreading is called metastasis. Although lymphoid tissue may be the primary site of cancer (e.g., lymphoma), it is more often the pathway of the metastatic process. Another major way cancer spreads is through blood.

Lymphatic vessels capture cancer cells as they penetrate the basal membrane of the altered tissue and travel to the underlying connective tissue. From there, the cancer cells enter the lymphatic capillaries and the lymphatic flow that carries them to the nearest lymph node. The first lymph node to drain the tumor is called the sentinel lymph node (SLN).

Pathological examination of the sentinel node is very important for the prognosis and advancement of the neoplasm. If the cancer cells are found only in the sentinel node, that is, the nearest lymph node, it is an indication that the tumor is in its early stages. On the other hand, if the tumor has invaded lymph nodes far from the original tumor, this may indicate that the tumor is at a later stage.

Also check: Tumors in numbers. More and more cancer patients

Lymphatic system support – exercises

Our heart serves as a pump to move blood throughout the body. The lymphatic system does not have this luxury, which is why movement and muscle contractions are so important to the lymph fluid

Many of the body’s lymph vessels run along the legs and arms, so any type of movement will provide stimulation. This can be as simple as walking during your lunch break or jogging at night. Simple household activities, such as gardening or vacuuming, can also be stimulating.

See also: Walking is the way to health

Lymphatic system support – diet

Eating a lean diet full of sweet, processed foods can slow down your lymphatic system and even cause drainage problems. An earlier study in mice fed a high-fat diet showed impairment of the function of the lymphatic system, and more specifically of the lymphatic vessels.

So what should you eat to strengthen your lymphatic system? Let’s try to eat fruits, vegetables, lean proteins and use herbs and spices. Fruits such as blueberries and oranges have antioxidant properties that benefit the health of your immune system. Nuts, seeds, and seafood contain omega-3 fatty acids, which are good for your lymphatic system.

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Lymphatic system support – deep breathing

Slow, controlled breathing can help increase the movement of lymph in our body. When we take a deep breath, the diaphragm expands and allows the lungs to engage the thoracic duct to stimulate the lymph fluid back into the bloodstream.

In patients with lymphedema, a condition that causes swelling, deep breathing can help the lymph flow back into the bloodstream to reduce the swelling. To practice deep breathing, breathe in slowly through your nose and exhale. You should also try to exhale twice as long as you inhale – this helps to increase the oxygen saturation in your blood.

Also check: Breathing exercises – indications, benefits, techniques. How to start breathing exercises?

Lymphatic system support – massages

Everyone likes a good massage to relieve aches and pains, but massages actually have a functional purpose to help restart the lymphatic system.

Known in medicine as lymphatic drainage, it is a type of massage that helps clear up any blockages in the lymphatic system that cause swelling. In some medical conditions, such as lymphoedema caused by breast cancer, swelling occurs when lymph fluid builds up in the arms and legs. The masseur uses certain techniques to help restore fluid movement.

Lymphatic system support – hydration

The lymph fluid is mostly water, so it’s important to stay hydrated. Dehydration can actually slow down the lymphatic system and affect the circulation of fluids and how waste is removed from the body.

If we start to feel lethargic or notice swelling, which may be due to problems with the lymphatic system, we should speak to our GP to discuss treatment options.

See also: Proper hydration of the body – why is it crucial?