How is oedema related to the lymphatic system in the body

It is the largest of our lymphatic organs. The spleen does many things as it filters and monitors our blood. As well as removing microbes, the spleen also destroys old or damaged red blood cells. It can also help in increasing blood volume quickly if a person loses a lot of blood.

The thymus is inside the ribcage, just behind the breastbone. It filters and monitors our blood content. It produces cells called T-lymphocytes which circulate around the body. These cells are important for cell mediated response to an immune challenge, such as may occur when we have an infection. Much of our digestive and respiratory system is lined with lymphatic tissue.

This lymphatic tissue plays a very important role in the defence of our body. Lymph nodes are filters. They are found at various points around the body, including the throat, armpits, chest, abdomen and groin. Generally they are in chains or groups All are imbedded in fatty tissue and lie close to veins and arteries. Lymph nodes have a wide range of functions but are generally associated with body defence. Bacteria or their products picked up from the tissues by cells called macrophages, or those that flow into the lymph, are forced to percolate through the lymph nodes.

There, white blood cells called lymphocytes can attack and kill the bacteria. Viruses and cancer cells are also trapped and destroyed in the lymph nodes. More lymphocytes are produced when you have an infection. That is why your lymph nodes tend to swell when you have an infection.

Those related to malformation or destruction or damage to the lymphatic system or its nodes include:. This page has been produced in consultation with and approved by:. A person with amyloidosis produces aggregates of insoluble protein that cannot be eliminated from the body.

When a person is anaemic, the red blood cells have to work harder to get oxygen around the body. An aneurysm may have no symptoms until it is either very large or it ruptures. Bleeding may be minor or it may be a life-threatening medical emergency. The lymphatic system can be thought of as a second circulatory system that runs in parallel, and in conjunction, with the cardiovascular system; it extends into every major region of the body, with the notable exceptions of the brain and spinal cord Moore and Bertram, The major anatomical components of the lymphatic system are highlighted in Fig 1.

Unlike the cardiovascular system, the lymphatic system is not a closed system and does not have a discrete pump analogous to the heart.

However, in many respects, the lymphatic vessels are structurally similar to veins: they have relatively thin walls and carry lymph under low pressure. For this reason, like veins, most of the larger lymphatic vessels are equipped with valves to prevent the backflow of lymph under the influence of gravity.

Lymph flows through several key lymphoid organs, where its composition is monitored and modified. The lymphoid organs are divided into:. The location and roles of the lymphoid organs are summarised in Table 1 and will be explored in more detail in subsequent articles in this series. The left ventricle of the heart ejects oxygen-rich blood under high pressure into the aorta, which is the major systemic artery.

Large arteries branch off the aorta to supply the upper and lower regions of the body with blood. Within the organs, arteries subdivide into progressively smaller vessels and eventually into the smallest arteries of the body, which are termed arterioles. Most arterioles connect to capillary beds, which permeate into the tissues Fig 2. The major role of capillaries is to distribute blood, ensuring adequate oxygen and nutrients are delivered to all cells, while simultaneously acting as conduits for:.

The flow of blood into capillary beds is regulated by small rings of smooth muscle called pre-capillary sphincters; when these are dilated open , blood from the arterioles flows in under high pressure. In most tissues, the capillary walls are porous, which allows fluid to be driven out through the capillary walls by a process called filtration. As this fluid collects in the small interstitial spaces that surround cells, it is referred to as interstitial fluid or tissue fluid.

Interstitial fluid bathes most human cells and has a composition similar to that of blood plasma, minus the larger plasma proteins that are too big to physically pass through the pores in the capillary walls.

The average adult human body has around L of interstitial fluid filling interstitial spaces, where it functions as the primary exchange medium in most human tissues. Freshly produced interstitial fluid is a complex mixture that is rich in oxygen and several other components, such as:.

As interstitial fluid is forced out at the arterial end of the capillary bed, the blood remaining in the capillaries is thicker and more viscous, and so moves more slowly.

It also has a higher concentration of soluble materials, such as plasma proteins albumin and fibrinogen, which exert an osmotic pull.

As a result, interstitial fluid rich in waste metabolites returns to the blood towards the venous end of the capillary bed, eventually draining into the venules to be carried away in the venous system. As this process is perpetual, the interstitial fluid surrounding the cells is continually being renewed and replaced. Without adequate drainage, excess interstitial fluid can accumulate in the tissues, leading to swelling oedema and, potentially, compression of local blood vessels and subsequent tissue damage.

The major role of the lymphatic system is to continually collect excess interstitial fluid and drain it away from the tissues. Interwoven among the capillary beds are blind-ended lymphatic capillaries Fig 2 ; the walls of these vessels are composed of cells that form overlapping flaps, which function as unidirectional mini-valves. Highly porous, they act like sponges, soaking up excess fluid from the interstitial spaces.

Unlike the larger lymphatic vessels, these lymphatic capillaries lack a muscular wall or internal valves; as such, they rely on capillary action to draw excess fluid away from the tissues and carry it to the progressively larger lymphatic vessels. As soon as interstitial fluid enters the lymphatic capillaries it is referred to as lymph; at this stage, newly formed lymph is usually a clear, transparent fluid that resembles water.

It was previously thought that the movement of lymph through the lymphatic system was a passive process, reliant on the physical movements of the body. As with veins, contraction of skeletal muscles compresses lymphatic vessels, raising the pressure inside with internal valves in the medium and larger lymphatic vessels ensuring a progressive upward movement of the lymph.

Although bodily movement does play an essential role, it has subsequently been discovered that the walls of larger lymphatic vessels are equipped with a specialised type of muscle, which is structurally intermediate between the smooth muscle that lines arteries and veins and the cardiac muscle located in the myocardium of the heart Scallan et al, This unique muscle type actively pumps by contracting in rhythmic waves similar to the peristaltic movements of the gastrointestinal tract , ensuring progressive, steady movement of lymph.

These rhythmic contractions of the lymphatic vessel walls complement the movement of lymph generated through bodily movement; they also ensure adequate movement of lymph while the body is stationary or at rest. Initially, in the smaller lymphatic vessels originating in the tissue capillary beds, lymph is usually transparent or straw-coloured, similar to plasma. This reflects its origins, and it is chemically virtually identical to interstitial fluid.

However, by the time it reaches larger lymphatic vessels, it has mixed with the products of fat digestion and takes on a cloudy or milky appearance; at this stage it is referred to as chyle. Lymph eventually enters the larger-diameter lymphatic vessels known as lymphatic trunks, which are equipped with robust valves to ensure lymph is progressively transported upwards against the pull of gravity. The thoracic duct terminates at and discharges its contents into the left subclavian vein, ensuring blood volume is maintained by recycling fluid that originated from the blood during capillary filtration.

At the point where the duct empties into the subclavian vein, a small bicuspid valve prevents backflow of venous blood into the lymphatic system Ilahi et al, Thoracic injuries, for example following a road traffic accident, can result in tearing of the thoracic duct and leakage of chyle into the pleural cavity.

This type of pleural effusion is known as a chylothorax and can lead to lung compression, making breathing difficult. Cellulitis is a bacterial infection of the deeper layers of skin and the fat and soft tissue layers under the skin. Lymphangitis : An inflammation of the lymph vessels can develop, and when infectious, it is usually caused by a Streptococcus bacterial infection. If left untreated, it can spread to the skin and adjacent soft tissues, causing cellulitis, or into the bloodstream, causing bacteremia.

Psychological effects : Lymphedema can affect the appearance, and this can have a psychological impact, especially in those who have been living with cancer. Lymphedema increases the risk of developing depression. The affected limb is more vulnerable to skin infections because the supply of lymphocytes which fight infection is reduced. If the patient takes measures to minimize the risk of cuts and grazes to the skin, their risk of subsequent infections may be significantly reduced.

The following measures may help:. The heavier a patient is, the higher the strain on the areas that are swollen. A healthy diet, aiming for an ideal body weight , may help alleviate the signs and symptoms of lymphedema.

There is no cure for lymphedema, and it is a progressive condition. The outlook will depend to some extent on the severity of symptoms.

Following a healthful lifestyle, including a balanced diet and movement or exercise can help reduce fluid buildup and stimulate the flow of lymph. A study identifies complex distinctions in genomes that help map the migrations of the Arabic people.

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Learn more. What is lymphedema? Medically reviewed by Stacy Sampson, D. Fast facts on lymphedema. Share on Pinterest Swelling is a typical symptom of lymphedema and commonly affects legs and arms.