The Lymphatic System

The lymph system, one of the most under-rated systems of the human body, arises from veins, developing from the existing vessels of the circulatory system. It is surprising to know that the lymphatic system is twice the size of the circulatory system and there is therefore twice as much lymph fluid as there is blood!

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Simply put, the Lymphatic (or Lymph) System acts as a collecting duct for excess fluids and as a filtering system to screen out foreign invaders. In essence the Lymph System is a complicated network of tubes spaced throughout the body which drain fluid (called lymph) from surrounding tissues and empties it back into the bloodstream.

The main functions of the system are to manage fluid levels and filter out bacteria, as well as containing white blood cells as part of our Immune System. Lymph fluid is filtered through the Spleen, Thymus and Lymph Nodes before being emptied back into the blood.

How the Lymphatic system works

As lymph capillaries carry lymph away from the tissue spaces and towards the heart, they merge to form larger and larger vessels. These larger vessels resemble veins, but their walls are thinner and they have more one-way valves to prevent lymph from flowing backwards. Whereas the cardiovascular system has a pump (the heart) to move blood through the system, the lymphatic system does not. It relies on the contraction of muscles to move lymph throughout the body, although the larger lymph vessels have a layer of smooth muscle in their walls that contract rhythmically to help pump lymph along. However, it is mainly the contraction of skeletal muscles from simple body movements and the action of breathing that moves lymph towards the heart. Therefore if you do not exercise or breathe deeply, lymph stagnates. This means that waste products remain in the lymph longer, reducing its ability to remove dead cells, toxins and allergens from healthy tissue promptly, causing severe stress on the immune system. With increased exposure to these toxins, the health of surrounding organs and tissues are compromised.

Progressively larger lymph vessels eventually unite to return lymph to the venous system through two ducts, the right lymphatic duct and the thoracic duct. Lymph that has been collected from the right arm and the right side of the head, neck and thorax (the area of the body between the neck and abdomen) empties into the right lymphatic duct. Lymph from the rest of the body drains into the thoracic duct, which is the body’s main lymph vessel, which in turn runs upward in front of the backbone. Both ducts then empty their lymph into the right and left subclavian veins, which lie under the collarbone. Both veins contain flaps which allow the lymph to flow into the veins, but prevent backflow. The subclavian vein empties into the superior vena cava which then empties into the right atrium of the heart.

Lymph Fluid

This comes from the Latin word lympha meaning “clear water”. Lymph is straw-coloured and is found within lymph vessels. Lymph fluid contains more white blood cells than but is similar to blood plasma (plasma is the clear fluid from blood minus the red pigment). In fact lymph fluid is made from blood plasma that leaks through blood vessels and is collected in the Lymph System. Lymph also carries other substances, depending on where it is collected in the body. From the limbs (arms and legs) the lymph is rich in protein, especially albumin. In the bone marrow, spleen and thymus high concentrations of white blood cells are found and in the intestine lymph fluid contains fats absorbed during digestion.

The Lymph Vessels

Unlike the circulatory system which brings blood to and from the heart, lymph vessels (also called lymphatics) only carry lymph fluid in one direction, towards the heart, through a spidery network of delicate tubes. Lymph capillaries (tiny vessels) have closed ends, unlike the circulatory system, which forms a circuit. Therefore they are structured to allow interstitial fluid, which bathes the cells, to pass in and out with ease. Lymph capillaries in the small intestine allow transportation of the products of digested fat such as fatty acids and Vitamin A. Blood capillaries cannot absorb protein and other large molecules dissolved in the interstitial fluid. The walls of the lymph capillaries allow material to pass through easily so these large molecules enter the lymph and are eventually returned to the blood.

The exchange of substances (oxygen, carbon dioxide, nutrients and wastes between the blood and the cells in the body occurs through the lymph capillaries. In an average person, roughly 25 litres of plasma fluid is forced out of the blood capillaries into the surrounding interstitial fluid which bathes the cells. After supplying cells with nutrients and picking up their wastes, 85% of this fluid is drawn back into the blood capillaries. The remaining 15% of fluid remains. If this amount of fluid were left to build-up even briefly, acute oedema (swelling caused by excessive body fluid) would result. If left further, the body would swell like a balloon, resulting in tissue destruction and eventual death. It is the presence of lymph capillaries that prevents this happening. The lymph capillaries runs alongside blood vessels between the tissue spaces, draining and absorbing the excess and eventually returning it to the venous blood just before it reaches the heart.


Lymphocytes are the primary cells that make up the Lymphatic system, being one-fourth of all white blood cells in the human body. Like all other white blood cells, they are produced in the bone marrow. Lymphocytes continuously travel through the body via tissue, blood or lymph vessels. There are two main classes of lymphocytes: T cells and B cells. The letter T refers to the thymus where T lymphocytes mature. B refers to the bone marrow where B lymphocytes mature. Approximately three-quarters of the circulating lymphocytes are T cells. They perform two main defensive functions. First they kill invaders and control the action of other lymphocytes involved in mounting an immune response. Additionally, T cells recognise and destroy any abnormal body cells, such as those which have become cancerous. B cells are also programmed to recognise specific antigens on invading cells and when stimulated by the entrance of these foreign cells, the B cells undergo a change in structure, producing protein compounds called anti-bodies, which bind with specific antigens (chemical markers) of foreign cells, effectively marking them for destruction.

The Lymph Nodes

Located among the route of lymph vessels are oval or kidney shaped structures called lymph nodes. These are made from lymphatic tissue and are the filters of the lymph system, ranging in size from microscopic to just under 1 inch in length. The smaller nodes are often referred to as nodules. These structures are often referred to in the context of cancer since they trap these malignant cells as they pass by and are an accurate guide to the health of the surrounding structures. There are between 500 and 1,500 lymph nodes located in the body, mostly occurring in clusters or chains. They usually appear grouped primarily in the neck, armpits, chest, abdomen, pelvis and groin. These nodes can usually be felt, but those appearing in the abdomen, pelvis and chest cannot. Those principal nodes at the neck, armpits and groins, are strategically placed at the junction where the extremities meet the trunk and serve to keep infection and injuries that introduce bacteria into the extremities away from the vital organs within the trunk.

Each node is housed in a fibrous capsule and is divided into spaces called sinuses. Lymph enters the nodes through several small vessels. The specialized tissue within the sinuses contains macrophages and lymphocytes, both types of white cells. Macrophages engulf and destroy bacteria and other foreign substances in the lymph. Macrophages and lymphocytes will rapidly divide if outnumbered by invading bacteria. This causes swelling and tenderness of the lymph nodes, which can often be felt. Once the lymph fluid has been filtered and cleansed it leaves the nodes through small lymph vessels.

Tonsils, Adenoids & Peyer’s Patches

These are small masses of lymphatic tissue that prevent infection in the body in areas where bacteria is abundant. Tonsils and adenoids are found in the back of the throat and nasal cavity. Peyer’s patches resemble tonsils and are found in the small intestine where their macrophages prevent infection by destroying bacteria constantly present in the moist environment of the intestine.

The other organs involved in the Lymphatic System:


The spleen is located under the ribs on the left side of your body. Although considered to be part of the lymphatic system, the spleen does not filter lymph (only lymph nodes do this). The spleen filters and cleans our blood of bacteria, viruses and other pathogens. It also destroys worn or old red blood cells. As blood flows through the spleen, macrophages line the tissues, engulfing and destroying both pathogens and worn out red blood cells, recycling the iron content and returning it to be formed into new blood cells. The spleen also stores blood and produces lymphocytes which are released into the bloodstream when needed. In addition during times of stress or injury when more blood is required, the spleen contracts releasing its supply to the circulation.


The thymus is a small gland under the breastbone that helps produce white blood cells. Your thymus shrinks in size as you age. In the growing foetus and in the infant child, immature lymphocytes are produced in the bone marrow. A certain class of these lymphocytes travels to the thymus where hormones change them into T lymphocytes or T cells. While they are maturing and multiplying in the thymus, T cells are trained to recognize the difference between cells that belong to the body and those that are foreign. Each T cell is programmed to respond to a specific chemical identification marker – called an antigen – on the surface of foreign or abnormal cells. Once they fully mature, T cells then enter the bloodstream and circulate to the spleen, lymph nodes and other lymphatic tissue.

Factors that affect the Lymph System

Apart from exercise and deep breathing, to keep lymph fluid moving, diet also plays a major factor. Specifically, high consumption of nutrient dead highly processed foods and meat and dairy products may be a prime factor in lymph disorders. In addition, an imbalance of Omega-6 to Omega-3 fatty acids is also highly suspect.

Toxic Chemicals

High levels of environmental toxicity and heavy metals also overwhelm the ability of the lymph system.

How to optimise your Lymphatic System

Liver health is linked to lymphatic health, as the liver produces the majority of lymph fluid, providing a major route for nutrients from the liver. The effectiveness of the lymph system is dependent on immune cells in the liver that filter out harmful bacteria and destructive yeasts. If liver function is compromised the lymphatic system suffers. Regular liver cleanses will improve the performance of the lymphatic system.

Lymphatic drainage massage can stimulate the system and increase the flow of lymph 20 times. Sauna and steam baths also help the lymph system by eliminating toxins through sweating.

Keep your Tonsils and Adenoids

Swollen tonsils and adenoids are merely a symptom of a problem, not the problem itself. They play an important role in the functioning of your immune and lymph system. Tonsils should never be removed before the age of 4. Before this age, they are a major supplier of the cells and proteins that help to protect from infection from viruses and bacteria. Even after age 4 they still play an important role. Like their related lymph nodes, they also swell up when over-burdened by foreign invaders. Removing them just weakens your defences. It should be noted that it is not unusual for tonsils and adenoids to swell temporarily at around age 8, especially in children eating large amounts of wheat, corn and dairy foods.

Herbs for the Lymphatic System

Cleavers (Galium aparine) Cleavers is generally considered to be the best lymphatic tonic. It is particularly effective in reducing glandular swellings in the neck and armpits.

Echinacea (Echinacea angustifolia) Echinacea combats both active microbial and viral infection.

Goldenseal (Hydrastis canadensis) Goldenseal has been used successfully against the Staphylococcus bacterium.

Marigold (Calendula officinalis) Marigold is commonly used where there are enlarged and inflamed lymphatic glands.

Myrrh (Commiphora molmol) Myrrh promotes an increase of white blood cells in support of the immune system.

Poke Root (Phytolacca decandra) Poke Root is a powerful herb used in deep-seated lymphatic problems, such as oedema, it is also effective against swollen glands, lymph nodes, mumps and tonsillitis. Poke Root has been known to inhibit cancer spreading through the lymph glands.

For advice or a consultation on managing lymphatic conditions please call 0845 468 0823; or fill in a consultation form.

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