Lymphatic system

Lymphatic System in Cardiovascular Medicine

Lymphatic system

The mammalian circulatory system comprises both the cardiovascular system and the lymphatic system. In contrast to the blood vascular circulation, the lymphatic system forms a unidirectional transit pathway from the extracellular space to the venous system.

It actively regulates tissue fluid homeostasis, absorption of gastrointestinal lipids, and trafficking of antigen-presenting cells and lymphocytes to lymphoid organs and on to the systemic circulation. The cardinal manifestation of lymphatic malfunction is lymphedema.

Recent research has implicated the lymphatic system in the pathogenesis of cardiovascular diseases including obesity and metabolic disease, dyslipidemia, inflammation, atherosclerosis, hypertension, and myocardial infarction.

Here, we review the most recent advances in the field of lymphatic vascular biology, with a focus on cardiovascular disease.

The recognition of the existence of lymphatic vessels has evolved slowly over the course of history, most importantly because of the difficulty of visualizing these transparent vessels. The first records of lymphatic vessels date back to ancient Greece, when Hippocrates (c. 460 to c. 370 BC) and Artistotle (c. 384 to c.

322 BC) documented vessels that may have been lymphatic vessels. Unequivocal reference to lymphatic vessels came from Alexandria, when dissenters including Erasistratus (c. 304 to c. 250 BC) described milky arteries in the mesentery.

In the 17th century, after a 2000-year gap, Gaspar Aselli can be credited for being the first to document functional lipid absorbing and transporting white veins in the mesentery of dogs that had consumed lipid-rich meals.

In the work that followed Aselli’s initial observations, it was established that these vessels made up a distinct vascular network that was separate from but connected to the blood vascular system. The gross anatomy of the lymphatic vessels was finally settled from the beginning of the 19th century.1,2

Because of the challenge of their visualization, lymphatic vessels have been historically ignored in research. Early anatomic studies relied primarily on intravascular injection of contrast agents.

2 However, the visualization of lymphatic endothelial cells (LECs) was revolutionized during the late 1990s through the identification of vascular endothelial growth factor receptor (VEGFR)-3,3 prospero homeobox 1 (PROX1) transcription factor,4 integral membane glycoprotein podoplanin (PDPN),5 and lymphatic vessel endothelial hyaluronan receptor 1 (LYVE1)6 as lymphatic-specific markers. Research in the field has bloomed during the 21st century through molecular genetic studies of developing embryos that have revealed >50 genes involved in the specification, expansion and maturation of lymphatic vessels, and in lymphovenous separation.7 Although classical studies have considered the lymphatic vasculature as a passive transit system from the extracellular space to the blood circulation, the lymphatic system has been identified to actively regulate numerous physiological and pathological processes. Moreover, lymphatic vessels have been identified in organs where they were previously not thought to exist, including the eye, where they are involved in intraocular pressure regulation,8–11 and in the central nervous system, where they drain cerebral interstitial fluid, cerebrospinal fluid, macromolecules, and immune cells.12,13 In addition, pioneering research has revealed lymph node (LN) LECs as antigen-presenting cells involved in the induction of peripheral tolerance.14 These seminal findings have opened unexpected avenues for research on the lymphatic vasculature.

In this review, we will update the state-of-the-art of the lymphatic system in development and disease pathogenesis with a special focus on cardiovascular diseases. For lymphangiogenesis in cancer, detailed mechanisms of developmental lymphangiogenesis, and the physiology of lymph propulsion, we would to refer the reader to several excellent reviews.7,15,16

Lymphatic Physiology

The lymphatic organ system is unique to vertebrates and is composed of draining lymphatic vessels, LNs, and associated lymphoid organs.

Un the blood vessels in the circulatory system, lymphatic vessels are blind-ended unidirectional absorptive vessels that transport interstitial fluid, immune cells, and macromolecules to the LNs, and from these back to the blood circulation (Figure 1).

The lymphatic vessels are found in almost every vascularized tissue except neural tissue and bone marrow. On the basis of their morphology, function, and hierarchy, lymphatic vessels are classified into capillaries (also known as initial lymphatic vessels), precollectors, and collectors (Figure 1A).

The capillaries (Figure 1B) converge into the larger collecting vessels (Figure 1C), which drain via chains of LNs (Figure 1D), leading eventually to the thoracic duct and the right lymphatic trunk; these drain into the venous circulation via four lymphovenous valves located at the junction of the subclavian and internal jugular veins18 (Figure 1E). The lymphatic vasculature plays an integral role in the regulation of tissue fluid homeostasis, immune cell trafficking, and absorption of dietary fats.

Figure 1.Organization of the lymphatic vascular tree.

A, In overview, the unidirectional lymphatic vascular system consists of (1) lymphatic capillaries, (2) collecting lymphatic vessels, (3) lymph nodes, and (4) the thoracic duct and right lymphatic trunk.

B, Lymphatic capillaries absorb interstitial solutes, macromolecules, and immune cells that extravasate from the blood vascular system.

Lymph formation is facilitated by the discontinuous basement membrane (red dashed line), and button- endothelial junctions allow passive paracellular flow for lymph formation. Adapted from Baluk et al17 with permission.

C, Collecting lymphatic vessels contain zipper- junctions, lymphatic valves, and contractile smooth muscle cells (SMCs) that enable the unidirectional propulsion of lymph. D, Organization of the lymph node with afferent lymphatic vessels and a single efferent lymphatic vessel. E, Lymph drains into venous circulation through 4 distinct lymphovenous valves located where the internal jugular vein (IJV) and external jugular vein (EJV) drain into the subclavian vein (SCV).

Tissue Fluid Homeostasis

Under physiological conditions, some of the intravascular blood plasma is constantly filtered through the semipermeable blood EC (BEC) layer into the extracellular space.

The majority of the extravasated interstitial fluid and macromolecules are absorbed back by the lymphatic vessels, whereas only transient reabsorption may occur in the venules.

19 Some tissues are exceptions, for example, the kidney and the intestinal mucosa, where venous fluid absorption is sustained by local epithelial secretions.

19 Overall, it has been estimated that the total plasma volume of the human body (≈3 L) extravasates from the blood circulation every 9 hours, and the great majority of this fluid is transported back to systemic circulation through the lymphatic system.

19 The lymphatic system is thus a major contributor to tissue fluid homeostasis (Figure 1).20 Mice with severe lymphatic defects often exhibit massive embryonic edema and lethality21; and if they survive until the neonatal period, they have severe problems caused by pulmonary edema.22 The systemic absence of the lymphatic vasculature thus seems to be incompatible with life. In adults, the cardinal manifestation of lymphatic dysfunction is lymphedema.

Lymphatic capillaries (initial lymphatic vessels) are composed of a single thin layer of LECs. These lymphatic capillaries have little basement membrane components, and lack mural cell coverage.

The oak-leaf–shaped LECs form overlapping flaps that are adherent to the adjacent ECs at their bases via button- junctions that are rich in tight junction-associated proteins and vascular endothelial cadherin.

17 These flaps operate as primary valves that allow unidirectional entry of lymph and immune cells.

23 LECs are tethered to the extracellular matrix with anchoring filaments that may modulate lymphatic drainage by opening the primary lymphatic valves in conditions of high interstitial pressure24 (Figure 1B).

These unique features make lymphatic capillaries highly permissive for the passive paracellular passage of fluid, macromolecules, and immune cells. However, it seems that active transcellular mechanisms may also contribute to lymph production, via transport of lipids25 and high-density lipoprotein (HDL),26 for example. In contrast to capillaries, the collecting lymphatic vessels are lined with LECs that are interconnected by tight zipper- junctions17 and surrounded by a continuous basement membrane.20

Contrary to the popular belief, lymphatic vessels do not function simply as a passive transit system but must actively overcome net pressure gradients that oppose flow. To do so, the collecting vessels contain intraluminal valves to prevent backflow and are covered by smooth muscle cells, which periodically contract to drive lymph forward.

In addition, extrinsic compression by the surrounding tissue during muscle activity significantly contributes to lymph propulsion. The lymphatic vessel segment flanked by 2 valves is called a lymphangion, a contractile unit that propels lymph into the next lymphangion through the interposed valve in a unidirectional manner16,20 (Figure 1C).

These intricate features of lymphatic physiology have been recently reviewed elsewhere.16

Immune Cell and Soluble Antigen Trafficking

Lymphatic vessels are crucial conduits not only for the trafficking of leukocytes from peripheral tissues to their draining LNs but also for the drainage of soluble antigens.

Although tissue resident dendritic cells (DCs) take up antigens and migrate to LNs for antigen presentation, soluble antigens transit to LNs faster than DCs, which is thought to prime the LN for the arrival of the antigen-presenting cells.

27 Interestingly, the entry of soluble antigens from the LN lymphatic sinuses to the reticular LN conduits occurs in a size-dependent manner. Although large antigens are taken up by subcapsular macrophages and paracortical DCs, small antigens (

Source: https://www.ahajournals.org/doi/10.1161/circresaha.115.306544

The lymphatic system and cancer

Lymphatic system

This page tells you about the lymphatic system and how cancer may affect it. There is information about

What the lymphatic system is

The lymphatic system is a system of thin tubes and lymph nodes that run throughout the body. These tubes are called lymph vessels or lymphatic vessels. The lymph system is an important part of our immune system. It plays a role in:

  • fighting bacteria and other infections
  • destroying old or abnormal cells, such as cancer cells

This video is about the lymphatic system, it lasts for 1 minute and 59 seconds.

Video of The lymphatic drainage system

Read a transcript of this video.

You can read detailed information about the immune system and cancer.

The lymphatic system

The diagram shows the lymph vessels, lymph nodes and the other organs that make up the lymphatic system.

How it works

The lymphatic system is similar to the blood circulation. The lymph vessels branch through all parts of the body the arteries and veins that carry blood. But the lymphatic system tubes are much finer and carry a colourless liquid called lymph.

The lymph contains a high number of a type of white blood cells called lymphocytes. These cells fight infection and destroy damaged or abnormal cells.

As the blood circulates around the body, fluid leaks out from the blood vessels into the body tissues. This fluid carries food to the cells and bathes the body tissues to form tissue fluid. The fluid then collects waste products, bacteria, and damaged cells. It also collects any cancer cells if these are present. This fluid then drains into the lymph vessels.

The lymph then flows through the lymph vessels into the lymph glands, which filter out any bacteria and damaged cells.

From the lymph glands, the lymph moves into larger lymphatic vessels that join up. These eventually reach a very large lymph vessel at the base of the neck called the thoracic duct. The thoracic duct then empties the lymph back into the blood circulation.

Lymph nodes (lymph glands)

The lymph glands are small bean shaped structures, also called lymph nodes.

There are lymph nodes in many parts of the body including:

  • under your arms, in your armpits
  • in each groin (at the top of your legs)
  • in your neck
  • in your tummy (abdomen), pelvis and chest

You may be able to feel some of them, such as the lymph nodes in your neck.

The lymph nodes filter the lymph fluid as it passes through them. White blood cells, such as B cells and T cells, attack any bacteria or viruses they find in the lymph.

When cancer cells break away from a tumour, they may become stuck in one or more of the nearest lymph nodes. So doctors check the lymph nodes first when they are working out how far a cancer has grown or spread.

When the lymph nodes are swollen, doctors call it lymphadenopathy. The most common cause is infection but lymph nodes can also become swollen because of cancer.

Other lymphatic system organs

The lymphatic system includes other organs, such as the spleen, thymus, tonsils and adenoids.

The spleen

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

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.

You might to read our information about how cancer starts. We also have information about how cancer can spread.  

For information about how cancer can affect the immune system, look at our page about the immune system and cancer.

Source: https://www.cancerresearchuk.org/what-is-cancer/body-systems-and-cancer/the-lymphatic-system-and-cancer

The lymphatic system

Lymphatic system

The lymphatic system runs throughout the body, your blood circulatory system. The lymphatic system carries a fluid called ‘lymph’ around the body in lymph vessels (tubes). The fluid passes through lymph nodes (glands), which are spread throughout your body.

Figure: The lymphatic system (lymph vessels and lymph nodes are shown in green)

The lymphatic system also includes organs and tissues that are places where immune system cells collect. These include the parts of the body that make cells for the immune system:

  • the bone marrow 
  • the thymus.

They also include areas where immune cells collect, ready to fight infection:

The lymphatic system defends your body against disease by removing germs (bacteria, viruses and parasites) and toxins (poisons). It also helps to destroy cells that are old, damaged or have become abnormal. It has other important functions too:

  • As a drainage system, it removes excess fluid and waste from your tissues and returns it to your bloodstream.
  • It helps to absorb fats and fat-soluble vitamins from your digestive system and to transport them to your bloodstream.

The whole of the lymphatic system helps to protect us against infection. Any part of it can be affected by lymphoma.

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Lymph

Lymph is a clear fluid that flows around the body in the lymphatic system. It is formed from plasma. Plasma is carried around your body in your blood vessels. It leaks the blood vessels and bathes your tissues and supplies the cells of your body with nutrients. Most of this plasma then drains back into the blood vessels. A small amount is left behind, together with:

  • waste products from the cells 
  • fat that is broken down in the bowel and needs to be carried to larger blood vessels
  • things that have got into the body and might be harmful, such as germs and toxins
  • damaged or abnormal cells, including cancer cells.

This all drains into tiny lymph vessels. Lymph vessels in the small intestine also absorb fats and fat-soluble vitamins.

When it is in lymph vessels, the fluid is known as ‘lymph’.

The lymph flows from the tiny lymph vessels into larger lymph vessels, heading towards one of two lymphatic ducts. The lymph filters through lymph nodes as it flows around your body.

The lymph nodes contain lots of lymphocytes (white blood cells that fight infection). Anything that doesn’t belong in your body, and any damaged and abnormal cells are removed in the lymph nodes. Lymph leaving the lymph nodes also carries lymphocytes.

These lymphocytes can fight infections elsewhere in the body if needed.

When the lymph reaches the lymphatic ducts, it goes into your bloodstream, draining into the large veins close to your heart. This removes excess fluid from around your body, helping to maintain your blood pressure and to avoid swelling.

Un blood, lymph is not pumped around your body by the heart. Instead, it is pushed along when your lymph vessels are squeezed by your muscles, and by gravity if the vessel is above the heart. It is a one-way system: valves stop any lymph flowing backwards.

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Lymph nodes

Lymph nodes are small, bean-shaped structures. They are usually around 1cm long, although this can vary depending on where they are in the body. There are thousands of them throughout the body.

Lymph nodes filter the lymph from nearby parts of the body.

Structure of a lymph node

Where are lymph nodes found?

There are lymph nodes at various points along the lymph vessels. They are often grouped together. There are groups of lymph nodes all around your body, except your brain and spinal cord. For example, groups of lymph nodes are found in the:

  • neck (cervical nodes)
  • armpits (axillary nodes)
  • groin (inguinal nodes)
  • centre of the chest between the lungs (mediastinal nodes)
  • abdomen, which is your tummy area.

Some lymph nodes can be felt from the outside if they swell up, for example those in the neck, armpit or groin. If these lymph nodes swell, you might be able to feel a lump in that area.

This often happens if you have an infection and is not usually a sign of something serious. There are also lots of lymph nodes deep within your body.

These lymph nodes can’t be felt from the outside but can be seen on scans.

How do lymph nodes work?

The lymph nodes filter the lymph passing through them. They trap germs (for example, bacteria) and cells of the immune system that give information about a nearby infection.

If there are signs of an infection, your body makes more lymphocytes to help fight the infection. As the number of lymphocytes builds up, the lymph nodes along the lymph vessels that drain the infected area swell. For example, an infection in the throat can cause the lymph nodes in your neck to swell.

When the infection has been destroyed, most of the immune system cells that were made in response to the infection die off. The lymph nodes normally return to their usual size in a couple of weeks. Most swollen lymph nodes are due to infections. If lymphoma cells collect in the lymph nodes, the swelling does not go down.

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Bone marrow

Bone marrow is the spongy material at the centre of many of your bones. It makes all the new blood cells you need, including red blood cells, platelets and the different white blood cells.

Bone marrow and the blood cells it produces

White blood cells are involved in the fight against infection. Lymphocytes are white blood cells that are part of the lymphatic system. They are the cells that become abnormal in lymphoma.

There are two types of lymphocytes: B lymphocytes (B cells) and T lymphocytes (T cells). Both are made in the bone marrow, then live throughout the lymphatic system.

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Thymus

The thymus is a small, butterfly-shaped gland in your chest. It sits behind your breastbone, just above your heart. It grows until puberty and then gradually shrinks in adults. T cells develop into fully working T cells in the thymus. When fully developed, they enter the bloodstream and lymphatic system.

As adults, T cells are maintained through division of mature T cells outside of the central lymphoid organs. 

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Spleen

The spleen is a pear-sized organ that lies just under your rib cage on the left-hand side of your body, behind your stomach. 

The spleen filters blood, much lymph nodes filter lymph. Immune system cells that live in your spleen remove germs, and old and damaged cells from your blood.

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Tonsils and adenoids

Your tonsils and adenoids are at the back of your throat and nose. They contain lots of immune system cells that help protect your body against infections that enter through the mouth and nose.

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Mucosa-associated lymphoid tissue

Mucosal tissue is the soft, moist, protective tissue that lines many parts of your body, for example your mouth, gut, breathing passages and other internal organs.

Mucosa-associated lymphoid tissue (MALT) is an area in the mucosa where lymphocytes and other immune system cells collect together. MALT can be found in the wall of the bowel (where it is known as ‘Peyer’s patches’) and in other organs, such as the lungs, eyes, nose and the thyroid gland.

MALT helps protect the body from infections and toxins entering through a part of the body lined by mucosa. The immune cells in MALT fight the infection or remove any toxins from your body.

MALT can form when healthy lymphocytes collect in tissue outside lymph nodes in response to an infection or inflammation (a reaction to injury, irritation or infection). This is a normal process. However, MALT lymphomas can develop when abnormal lymphocytes collect in this lymphoid tissue.

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The lymphatic system and lymphoma

Lymphocytes are part of the lymphatic system and are spread throughout the body. When lymphocytes become abnormal, lymphoma can develop. Lymphoma can therefore develop in almost any part of the body.

It is also easy for lymphoma to spread throughout the body in the lymphatic system. Un other cancers, most people with lymphoma have it in more than one place when they are diagnosed.

Lymphoma that is in lots of places in the body can be successfully treated and often cured.

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Source: https://lymphoma-action.org.uk/about-lymphoma-what-lymphoma/lymphatic-system

Lymphatic System Anatomy: Overview, Gross Anatomy, Other Considerations

Lymphatic system

Lymph is a fluid derived from blood plasma. It is pushed out through the capillary wall by pressure exerted by the heart or by osmotic pressure at the cellular level.

Lymph contains nutrients, oxygen, and hormones, as well as toxins and cellular waste products generated by the cells.

As the interstitial fluid accumulates, it is picked up and removed by lymphatic vessels that pass through lymph nodes, which return the fluid to the venous system. As the lymph passes through the lymph nodes, lymphocytes and monocytes enter it.

At the level of the gastrointestinal (GI) tract, lymph has a milky consistency that is attributable to fatty acids, glycerol, and rich fat content. Lacteals are lymph vessels that transport intestinal fat and are localized to the GI tract. [1, 5, 3]

Lymphatic capillaries are blind-ended tubes with thin endothelial walls (only a single cell in thickness).

They are arranged in an overlapping pattern, so that pressure from the surrounding capillary forces at these cells allows fluid to enter the capillary (see the image below).

The lymphatic capillaries coalesce to form larger mesh networks of tubes that are located deeper in the body; these are known as lymphatic vessels.

Lymph capillaries in spaces. Blind-ended lymphatic capillaries arise within interstitial spaces of cells near arterioles and venules.

The lymphatic vessels grow progressively larger and form 2 lymphatic ducts: the right lymphatic duct, which drains the upper right quadrant, and the thoracic duct, which drains the remaining lymphatic tributaries.

veins, lymphatic vessels have 1-way valves to prevent any backflow (see the image below).

The pressure gradients that move lymph through the vessels come from skeletal muscle action, smooth muscle contraction within the smooth muscle wall, and respiratory movement. [1, 6, 2, 5, 4, 7]

Lymphatic 1-way valves.

Lymph nodes are bean-shaped structures that are widely distributed throughout the lymphatic pathway, providing a filtration mechanism for the lymph before it rejoins the blood stream.

The average human body contains approximately 600-700 of them, predominantly concentrated in the neck, axillae, groin, thoracic mediastinum, and mesenteries of the GI tract.

Lymph nodes constitute a main line of defense by hosting 2 types of immunoprotective cell lines, T lymphocytes and B lymphocytes.

Lymph nodes have 2 distinct regions, the cortex and the medulla. The cortex contains follicles, which are collections of lymphocytes.

At the center of the follicles is an area called germinal centers that predominantly host B-lymphocytes while the remaining cells of the cortex are T-lymphocytes.

Vessels entering the lymph nodes are called afferent lymphatic vessels and, wise, those exiting are called efferent lymphatic vessels (see the image below).

Lymph node structure.

Extending from the collagenous capsule inward throughout the lymph node are connective tissue trabeculae that incompletely divide the space into compartments.

Deep in the node, in the medullary portion, the trabeculae divide repeatedly and blend into the connective tissue of the hilum of the node. Thus the capsule, the trabeculae, and the hilum make up the framework of the node.

Within this framework, a delicate arrangement of connective tissue forms the lymph sinuses, within which lymph and free lymphoid elements circulate.

A subcapsular or marginal sinus exists between the capsule and the cortex of the lymph node. Lymph passes from the subcapsular sinus into the cortical sinus toward the medulla of the lymph node.

Medullary sinuses represent a broad network of lymph channels that drain toward the hilum of the node; from there, lymph is collected into several efferent vessels that run to other lymph nodes and eventually drain into their respective lymphatic ducts (see the image below). [1, 6]

Lymph drainage flow; lymphatic duct anatomy.

The thymus is a bilobed lymphoid organ located in the superior mediastinum of the thorax, posterior to the sternum. After puberty, it begins to decrease in size; it is small and fatty in adults after degeneration.

The primary function of the thymus is the processing and maturation of T lymphocytes. While in the thymus, T lymphocytes do not respond to pathogens and foreign organisms.

After maturation, they enter the blood and go to other lymphatic organs, where they help provide defense. Structurally, the thymus is similar to the spleen and lymph nodes, with numerous lobules and cortical and medullary elements.

It also produces thymosin, a hormone that helps stimulate maturation of T lymphocytes in other lymphatic organs. [2, 5, 3, 4]

The spleen, the largest lymphatic organ, is a convex lymphoid structure located below the diaphragm and behind the stomach.

It is surrounded by a connective tissue capsule that extends inward to divide the organ into lobules consisting of cells, small blood vessels, and 2 types of tissue known as red and white pulp.

Red pulp consists of venous sinuses filled with blood and cords of lymphocytes and macrophages; white pulp is lymphatic tissue consisting of lymphocytes around the arteries. Lymphocytes are densely packed within the cortex of the spleen.

The spleen filters blood in much the same way that lymph nodes filter lymph. Lymphocytes in the spleen react to pathogens in the blood and attempt to destroy them.

Macrophages then engulf and phagocytose damaged cells and cellular debris. The spleen, along with the liver, eradicates damaged and old erythrocytes from the blood circulation.

other lymphatic tissue, it produces lymphocytes in an immunologic response to offending pathogens. [5, 3, 4]

Therefore, the spleen conducts several important functions, as follows:

  • It serves as a reservoir of lymphocytes for the body
  • It plays an important role in red blood cell and iron metabolism through macrophage phagocytosis of old and damaged red blood cells
  • It recycles iron by sending it to the liver
  • It serves as a storage reservoir for blood
  • It contains T lymphocytes and B lymphocytes for immunologic response

Tonsils are aggregates of lymph node tissue located under the epithelial lining of the oral and pharyngeal areas. The main areas are the palatine tonsils (on the sides of the oropharynx), the pharyngeal tonsils (on the roof of the nasopharynx; also known as adenoids), and the lingual tonsils (on the base of the posterior surface of the tongue).

Because these tonsils are so closely related to the oral and pharyngeal airways, they may interfere with breathing when they become enlarged. The predominance of lymphocytes and macrophages in these tonsillar tissues offers protection against harmful pathogens and substances that may enter through the oral cavity or airway. [1, 2]

Source: https://emedicine.medscape.com/article/1899053-overview

FAQs About the Lymphatic System

Lymphatic system

Lymphatic disease is a malfunction of the lymphatic system in which fluid, or lymph, does not pass properly through the lymph nodes and lymphatic vessels. The most common lymphatic disease is lymphedema. The most prevalent lymphatic disorder is lymphatic insufficiency, or lymphedema.

This is an accumulation of lymphatic fluid in the interstitial tissue causing swelling, most often in the arm(s) and/or leg(s), and occasionally in other parts of the body. The severity of this disease varies from very mild complications to a disfiguring, painful and disabling condition.

In addition, patients are often susceptible to serious life-threatening cellulite infections (deep skin), and if untreated, can spread systemically or require surgical intervention. It remains a lifelong functional problem requiring daily treatment for maintenance.

Eventually the skin becomes fibrotic (thickening of the skin and subcutaneous tissues) with loss of normal architecture, function and mobility.

There are two main types of chronic lymphedema: Primary and Secondary

Primary Lymphedema is an inherited disease that affects approximately 0.6% of live births and in which there is a congenital defect of the lymph-transporting system.

It can be present at birth, develop at the onset of puberty or present in adulthood, with no apparent causes.The lymphatic system does not develop properly.

Those affected with Primary lymphedema will have swelling of various parts of the body due to the accumulation of lymph.

Nonne- Milroy’s lymphedema is characterized by swelling of one or both legs, arms, and/or face with gradual fibrotic changes.

Meige’s Syndrome-develops after the onset of puberty

Lymphedema Tarda- usually develops after the age of 35

Lymphedema-distichiasis may also present after puberty and patients have an auxiliary ( extra) set of eyelashes.

A number of the hereditary lymphedema conditions can be linked to a gene mutation  ( flt4 ;FOXC2)

There are several chromosomal disorders in addition that have been associated with lymphatic conditions including lymphedema.  Gorham’s Disease, Turner Syndrome, Klippel-Trenaunay Syndrome, Yellow Nail Syndrome, Noonan Syndrome are just some of these associated conditions.

Lymphangioma- a congenital lymphatic malformation that arises during embryonic development is another lymphatic condition. Lymphangiomatosis is the presence of multiple or widespread lymphatic vascular malformations.

Protein-Losing Enteropathy may occur in the presence of Intestinal lymphangiectasia. Those affected have excessive protein loss into the gastrointestinal lumen leading to hypoproteinemia. This leads to severe edema, in addition to ascites (excess abdominal fluid in the abdomen) and pleural effusion (excess fluid in the cavity lining the lung)

Congenital Pulmonary Lymphangiectasia- abnormally dilated ( widened) lymphatic vessels within the lungs leads to lymph collecting in the lungs and leads to respiratory distress.

Secondary Lymphedema (acquired regional lymphatic insufficiency) is a disease that is common among adults and children in the United States. It can occur following any trauma, infection or surgery that disrupts the lymphatic channels or results in the loss of lymph nodes.

Among the more than 3 million breast cancer survivors alone, acquired or secondary lymphedema is believed to be present in approximately 30% of these individuals, predisposing them to the same long-term problems as described above.

Lymphedema also results from prostate, uterine, cervical, abdominal, orthopedic cosmetic (liposuction) and other surgeries, malignant melanoma, and treatments used for both Hodgkin's and non-Hodgkin's lymphoma. Radiation, sports injuries, tattooing, and any physical insult to the lymphatic pathways can also cause lymphedema.

Even though lymphatic insufficiency may not immediately present at the time any of the events occur, these individuals are at life-long risk for the onset of lymphedema.

Lymphatic Filariasis is a world health problem resulting from a parasitic-caused infection causing lymphatic insufficiency, and in some cases predisposes elephantiasis. The World Health Organization's recent efforts to eradicate the spread of infection do not address or eliminate the resulting lymphedema.

Lymphoma is a type cancer that begins in infection-fighting cells of the immune system called lymphocytes.

The lymphatic system includes the lymph nodes, spleen, thymus, bone marrow, and other parts of the body. When you have lymphoma, these areas are affected as well as other organs in the body.

There are two main types of lymphoma:  Non-Hodgkin (most people with lymphoma have this type) and Hodgkin.

Non-Hodgkin and Hodgkin lymphoma each affect a different kind of lymphocyte. Every type of lymphoma grows at a different rate and responds differently to treatment.

Source: https://lymphaticnetwork.org/living-with-lymphedema/lymphatic-disease

Spleen and Lymphatic System

Lymphatic system

The spleen is located in the upper left part of the belly under the ribcage. It helps protect the body by clearing worn-out red blood cells and other foreign bodies (such as germs) from the bloodstream.

The spleen is part of the lymphatic system, which is an extensive drainage network. The lymphatic (lim-FAT-ik) system works to keep body fluid levels in balance and to defend the body against infections. It is made up of a network of lymphatic vessels that carry — a clear, watery fluid that contains proteins, salts, and other substances — throughout the body.

What Does the Spleen Do?

The spleen acts as a filter. It weeds out old and damaged cells and helps control the amount of blood and blood cells that circulate in the body.

The spleen also helps get rid of germs. It contains white blood cells called and macrophages. These cells work to attack and destroy germs and remove them from the blood that passes through the spleen.

The body also uses the spleen as a place to store blood and iron for future use.

What Does the Lymphatic System Do?

One of the lymphatic system's major jobs is to collect extra lymph fluid from body tissues and return it to the blood.

This is important because water, proteins, and other substances are always leaking tiny blood capillaries into the surrounding body tissues.

If the lymphatic system didn't drain the excess fluid, the lymph fluid would build up in the body's tissues, making them swell.

The lymphatic system is a network of very small tubes (or vessels) that drain lymph fluid from all over the body. The major parts of the lymph tissue are located in the:

  • bone marrow
  • spleen
  • thymus gland
  • tonsils

The heart, lungs, intestines, liver, and skin also contain lymphatic tissue.

The major lymphatic vessels are:

  • the thoracic duct: It begins near the lower part of the spine and collects lymph from the pelvis, abdomen, and lower chest. The thoracic duct runs up through the chest and empties into the blood through a large vein near the left side of the neck.
  • the right lymphatic duct: It collects lymph from the right side of the neck, chest, and arm, and empties into a large vein near the right side of the neck.

The lymphatic system also helps defend the body against germs (viruses, bacteria, and fungi) that can cause illnesses. Those germs are filtered out in the lymph nodes, small clumps of tissue along the network of lymph vessels.

Inside the lymph nodes, lymphocytes called T-cells and B-cells help the body fight infection.

B cells make antibodies — special proteins that stop infections from spreading by trapping disease-causing germs and destroying them.

Most of our lymph nodes are in clusters in the neck, armpit, and groin area. They're also found along the lymphatic pathways in the chest, abdomen, and pelvis, where they filter the blood.

When a person has an infection, germs collect in the lymph nodes. If the throat is infected, for example, the lymph nodes in the neck may swell. That's why doctors check for swollen lymph nodes (sometimes called swollen “glands”) in the neck when someone has a sore throat. This is called lymphadenopathy.

Reviewed by: Larissa Hirsch, MD

Date reviewed: August 2019

Source: https://kidshealth.org/en/teens/spleen.html

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