The key function of lymph is to transport blood components back to the blood stream and maintain the correct volume of blood circulation. Interstitial fluid is fluid which has leaked from the blood circulation and contains blood cells and proteins which are essential components of blood.
Once absorbed into the lymphatic system, the interstitial fluid becomes known as lymph and travels through the lymphatic vessels to the subclavian veins where it re-enters the blood circulation and maintains blood volume.
Lymph is the substance in which escaped blood cells and proteins are collected and returned to the blood circulation. However, only a proportion of the interstitial fluid which enters the lymphatic capillaries will be returned to the blood stream as lymph; the remainder is broken down in the lymph nodes. An average human body weighing 65 kg contains approximately 12 litres of interstitial fluid and produces 8—12 litres of lymph each day. Because gravity makes it harder for lymph to be transported from the legs and the lower half of the body, lymphatic capillaries which absorb lymph are more extensive in the legs compared to the arms.
Lymphatic vessels connect to the subclavian veins, which are part of the blood circulatory system and connect to the heart.
Their key function is to transport excessive tissue fluid from interstitial spaces throughout the body back to the blood stream. These vessels form a unidirectional system which always directs lymph toward the heart. The key function of the capillaries of the lymphatic system is to absorb fluid leaked from the blood vessels into the interstitial spaces.
Known as interstitial fluid it is predominately water but contains a small amount of dissolved proteins and sometimes larger particles including debris e. Together with blood vessels the lymphatic capillaries also function to ensure that circulation through the surrounding cells and tissues is sufficient to ensure each cell gets enough nutrients, and also to ensure the cells and tissues are drained so that the fluid balance is constant.
The flap-like structures on the walls of lymphatic capillaries function to increase absorption when there is too much fluid in the interstitial spaces, and reduce absorption when the fluid level decreases.
When fluid levels in the interstitial spaces increase, they create pressure which causes the flap-like structures of the capillary walls to open, allowing fluid to enter the lymph capillaries. The flaps may open up to several micrometres. As the lymphatic capillary and vessel fill with fluid, pressure inside the capillaries increases. When pressure inside the lymphatic capillary increases above that in the surrounding interstitial space, the flaps in the capillary wall close, preventing the fluid which has been absorbed escaping back into the interstitial space.
Fluid is then pushed through the lymphatic capillaries to the collecting vessels. However, the lymphatic system does not have a central pump like the heart which pumps fluid through the blood vessels. In the lymphatic system, fluid is pushed by spontaneous contractions of the lymphatic capillaries and other lymphatic vessels. These contractions are regulated by the nervous system and some hormones, and are the force which drives lymph through the lymphatic vessels.
Collecting vessels transport lymph from the lymphatic capillaries to the lymphatic ducts, via numerous lymph nodes. Muscles in the walls of collecting vessels contract to push the lymph through the vessels. Contractions in the arteries and skeletal muscles, breathing, blood pressure and the volume of lymph in the lymphatic system also influence the rate at which lymph is pushed through the lymphatic vessels.
Valves along the walls of collecting vessels function to prevent the lymph from flowing backwards. Pre-nodal vessels transport afferent lymph to the lymph nodes. They also transport immune cells e. Dendritic cells, also called antigen presenting cells, present antigens to immune cells called T lymphocytes, which are capable of destroying but not recognising the antigens.
T lymphocytes only recognise antigens when they are presented by dendritic cells. Dendritic cells circulate throughout the body via the blood and lymph circulation and they typically come into contact with the antigens they will present to the T lymphocytes in peripheral organs like the stomach and skin. However, they do not present the antigens in the peripheral organs.
Lymph nodes which contain abundant lymphocytes, provide the optimal environment for the presentation of antigens to T-lymphocytes. Thus dendritic cells and the antigens they wish to present must move into the interstitial spaces surrounding the organs and from there be absorbed into the lymphatic capillaries and transported to the lymph nodes via the afferent vessels.
Once in the lymph node they can be presented to the T lymphocytes for recognition and destruction. The right lymphatic duct transports lymph collected from the right arm, the right side of the head and the thorax, to the blood circulation, via the right subclavian vein. The left thoracic duct drains lymph from the remainder of the body and transports it to the blood circulation via the left subclavien vein. Specific immune responses immune responses involving the production of antibodies to fight against a specific antigen are initiated in the lymph nodes, and antigen presentation by dendritic cells , recognition and destruction by T lymphocytes occur there.
The lymph nodes are also the places where antibody-producing B lymphocytes undergo final maturation and begin to produce clone cells replicas. These may be either antibody-releasing plasma cells cells which recognise and produce antibodies against a specific antigen such as varicella virus which causes chicken pox or memory B lymphocytes those which remember specific antigens and enable the immune system to respond quickly the next time they encounter the antigen. Lymph nodes are immune system checkpoints at which lymph being transported back to the blood vessels is inspected and filtered of foreign matter, including antigens.
Particles such as viruses and bacteria generally cannot enter the blood stream directly via blood capillaries as the openings in the blood capillaries are too small for them to pass through.
The lymphatic capillaries, however, have larger openings which are big enough to allow relatively large particles including microorganisms and cancer cells, to enter. Following entry to the lymphatic system these particles may travel to distant body sites and enter the blood stream where they can disperse and cause infection unless they are removed at the lymph nodes.
The lymph nodes contain an abundance of B and T lymphocytes and macrophages which perform inspection and filtering functions. As lymph travels through the lymphatic vessels to the heart, lymph passes slowly through lymph nodes allowing time for immune cells within the node to perform their protective functions. Typically lymph will be cleansed of foreign particles after flowing through several nodes. However, when the nodes are overwhelmed by high concentrations of foreign matter as when someone is ill due to infection , they become swollen, causing symptoms such as swollen glands.
Cleansing efficiency of the nodes is reduced at these times, which means that more foreign matter passes through the lymph node and enters the blood. As afferent lymph passes through a lymph node, the macrophages in it are removed. The processes by which lymph nodes clear macrophages and the fate of the millions of macrophages which vanish every day from a single lymph node weighing just 1 gram, is not well understood. A key function of the spleen which, like the lymph nodes, contains T and B lymphocytes as well as macrophages, is to filter blood of viruses, bacteria and other foreign matter.
It also destroys ageing red bloods cells and defective cells. This means that they cannot get through the small slits which filter blood in the spleen. These cells are then removed from within the spleen by macrophages. When red bloods cells are broken down, some of their components are returned to the liver.
For example, iron which is used by the liver to produce haemoglobin, is an important component of blood. Iron is one of the by-products of red blood cell breakdown which is transferred to the liver. The spleen works in conjunction with the liver to maintain blood volume during times of bleeding.
It contains large amounts of blood that is periodically released into the circulation by contraction of a muscle in the spleen. Both the liver and spleen release the large amounts of blood they contain to the blood circulation in order to replace blood lost through bleeding. The thymus is a hormone producing gland. Thymosin and other hormones it produces regulate the maturation and differentiation of T lymphocytes.
Only when they are mature are T lymphocytes capable of performing the immune function of destroying antigens. T lymphocytes are produced in the bone marrow but transit the thyroid before entering blood circulation. Not all the lymphocytes which enter the thymus continue on to the blood circulation. The thymus selects those lymphocytes which are efficient at recognising specific antigens and preferentially matures these lymphocytes.
It also recognises T lymphocytes which recognise normal parts of the body as antigens, and prevents them from maturing. T lymphocytes destroy antigens, so if they incorrectly recognise parts of the healthy body as antigens, they will begin destroying healthy body cells.
Thus those that recognise self-antigens are destroyed in the thymus before they can enter the body and start attacking antigens. The T lymphocytes selected by the thymus for maturation are then released to the lymph nodes. Disorders of the lymph nodes are uncommon but result in severe oedema fluid accumulation which causes swelling when they do occur. Examples of disorders of the lymph nodes include:. Primary lymphoedema is a congenital disorder a disorder acquired at birth of the lymphatic system which is relatively rare compared to acquired or secondary lymphoedema which may arise following surgery or infection with a parasite.
Primary lymphoedema is characterised by widened lymphatic capillaries which results in accumulation of fluid in the interstitial spaces. View more information about myVMC. Please be aware that we do not give advice on your individual medical condition, if you want advice please see your treating physician. Parenting information is available at Parenthub. Are you a Health Professional?
Jump over to the doctors only platform. Click Here. Lymphatic System. The microscopic lymph capillaries merge to form lymphatic vessels. Small lymphatic vessels join to form larger tributaries, called lymphatic trunks , which drain large regions.
Lymphatic trunks merge until the lymph enters the two lymphatic ducts. The right lymphatic duct drains lymph from the upper right quadrant of the body. The thoracic duct drains all the rest. Like veins , the lymphatic tributaries have thin walls and have valves to prevent backflow of blood. There is no pump in the lymphatic system like the heart in the cardiovascular system. From what I was taught it is not beneficial for treating lymphedema but my employer feels that it is.
Dear Nadia: Advanced and newer compression pumps consist of multi-chambered inflatable sleeves that include trunk garments containing inflatable chambers designed to prepare drainage areas on the trunk prior to moving fluid from the extremities.
Pneumatic compression used to treat extremity lymphedema without treatment of adjacent body quadrants and drainage areas using complete decongestive therapy bears a significant risk of moving lymphedemateous fluid from distal to proximal, where it accumulates. This may cause protein molecules to accumulate in this area, forming a fibrosclerotic ring, truncal quadrants previously not swollen to fill with fluid, or external genitalia to swell.
Recent studies suggest that multi-chambered sequential compression devices that include trunk and extremity garments and deliver the pressurized air in individual patient-oriented patterns may be beneficial as an adjunct treatment to effectively control lymphedema in the self-administered maintenance phase Phase II of CDT , especially in those cases when physical limitations of the patient may result in challenges controlling the lymphedema independently with self-MLD.
Men consider me undateable! Is there any help? Dear Radha: I would suggest youseek the assistance of a trained lymphedema therapist to control your swelling. I have developed axillary web syndrome without ever having had any surgery of breasts or lymph nodes or that area. Does that mean I have cancer? Kate: Developing cord-like symptomes certaily does not mean that you have cancer. The cords could be any form of fibrosis and your doctor should be able to evaluate. Subscribe in a reader.
The information on this web site is not intended to give medical advice and does not necessarily reflect the opinions of any physicians, nor is it guaranteed to be correct and complete. You should not rely on any information in this web site without seeking the advice of a physician or certified healthcare provider.
Discuss on our WP Forum. Joachim Zuther, Lymphedema Specialist. Read more. Primary Lymphedema. Secondary Lymphedema. Other Conditions. Complications of Lymphedema. Traveling with Lymphedema. Lymphedema Therapists.
Articles on Lymphedema. Comparison of Blood and Lymph Vessels. Tweet The heart and blood vessels represent the main components of the circulatory system, which consists of an elaborate network of tubes throughout the body. Lymphedema Resources , Lymphedemablog News Blood vessels and lymph vessels , difference between blood and lymph vessels , lymphatic anatomy , lymphedema blog , lymphedema information , lymphedema news , lymphedema resource.
February 15, at pm. Joachim Zuther. Julie Green.
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