The Lymphatic/Immune System and Its Disorders
Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss in Understanding Medical Terms, 2020
To move the lymph along its course, the system incorporates a pumping mechanism. All lymph vessels contain lymphatic valves, also known as valvulae lymphatica (singular: valvula lymphaticum). As a lymphatic vessel fills with lymph, it contracts in response to being stretched. The contraction forces the lymph past the lymphatic valve and into the next section of the vessel, and the valve closes from the back pressure as that new section begins to contract. Additionally, pressure is applied to the lymphatics by muscle movement, and even arterial pulsations during exercise compress the lymphatics, moving lymph along the channel. In the initial lymphatics, contraction or pressure causes the channels between overlapping endothelial cells to close, and the anchoring ligaments squeeze the lymphatic capillary as the surrounding cells move.
Microcirculation
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal in Principles of Physiology for the Anaesthetist, 2020
The lymphatic capillaries arise in the tissues and drain lymph – a fluid derived from interstitial fluid – through the lymph nodes and progressively larger vessels that open into the right and left subclavian veins. Only central nervous system tissues, cartilage, bone and epithelium do not have lymph vessels. Tissue lymph vessels are thin-walled, like capillaries but blind-ended. The lymphatic channels contain valves that ensure that the flow of lymph is in one direction, from the interstitial fluid back into the cardiovascular system. The lymphatic capillaries are the first vessels of the lymphatic system; no other vessels drain into them. The walls of lymphatic capillaries consist of one layer of endothelium and are permeable to fluid and protein. The lymphatic endothelial cells also contain a few contractile actin–myosin filaments.
Adaptive Tumor Suppression
John Melford in Pocket Guide to Cancer, 2017
Among the components of the adaptive system are specialized white blood cells called lymphocytes of which there are two main types, B-cells and T-cells. These are created in the bone marrow by stem cells, and then circulate in the blood. T-cells migrate to the thymus where they reach maturity, hence the name T-cells. Mature B-cells and T-cells are deployed to lymph nodes and other lymphoid organs where they remain on alert to respond to a pathogen invasion. The lymphatic system consists of an extensive network of vessels that connect lymph nodes, the thymus, the spleen, adenoids, and tonsils. Lymph vessels are like arteries and veins that carry vital supplies of blood to all parts of the body. However, they are much finer and carry a colorless liquid called lymph. The primary function of the lymphatic system is to transport lymph, a fluid containing white blood cells, throughout the body. Unlike the blood system, which uses a pump to circulate fluid, movements of the body drive the circulation of the lymphatic system. This is a good reason to exercise regularly. There are hundreds of lymph nodes that serve as traps for pathogens, cancer cells and toxins to facilitate their removal. Thus, swollen lymph nodes may be indicative of an infection or a tumor. Those caused by infections come and go as we become ill and recover. Those caused by cancers are likely to persist.
Thoracic Lymph Duct Catheterization with a Venous Shunt in the Nonhuman Primate
Published in Journal of Investigative Surgery, 2022
Jon Ehrmann, Claudia Generaux, Sharon Ostergaard, Wendy Johnson, Anne Rose, Vince Mendenhall
The structural composition of the lymphatic duct posed a few challenges regarding catheterization. The lymphatic vessel is a thin walled valved structure, so thin in fact it appears transparent when held up against forceps. Due to their delicate nature, it was important to only dissect out a small amount of the vessel to preserve the integrity of the structure and allow for catheterization. It was also important to allow the duct to backfill with lymph and build up pressure once it was ligated which increased the size of the duct and helped maintain its structure during catheterization. Once the duct was void of lymph it was exceedingly difficult to manipulate the duct and find the incision into the duct for catheterization. On a few occasions, advancement of the catheter within the duct was significantly limited due to the presence of unidirectional valves which prevented catheter advancement. In those instances, the catheter was removed, the duct was ligated distal to the original insertion point and catheterization was attempted again downstream of the valve.
Modelling uptake and transport of therapeutic agents through the lymphatic system
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
T. D. Jayathungage Don, V. Suresh, J. E. Cater, R. J. Clarke
Consequently, computational models can play an important role in quantifying lymphatic drainage. In this regard, however, the lymphatic system has received much less attention than its cardiovascular counterpart. Many of the existing models focus on a specific feature of the lymphatic vessel physiology. For example, Reddy and Patel (Reddy and Patel 1995) developed a two-dimensional mechanical model of a lymphatic capillary pore, and considered the opening mechanism which occurs when anchoring filaments are placed under tension by the surrounding tissue. Mendoza and Schmid-Schönbein (2003) have also considered the capillary pore mechanics, treating them as junctions that can open by bending under an applied loading. This was later extended by others through the addition of the interstitium, and consideration of the junction’s nonlinear mechanics (Galie and Spilker 2009).
The Histopathological Findings of Patients Who Underwent Blepharoplasty Due to Dermatochalasis
Published in Seminars in Ophthalmology, 2018
Ali Karnaz, Yasemin Aslan Katircioglu, Evin Singar Ozdemir, Pınar Celebli, Sema Hucumenoglu, Firdevs Ornek
Normal lymphatic vessels cannot be easily distinguished owing to their thin endothelial cells and narrow lumens in normally functioning skin.22 Lymphatic vessels that are easily discerned owing to dilation secondary to obstruction or impaired lymphatic flow exhibit certain histological findings such as thinned walls, sparse endothelial cells, and lymph valves.22,23 Therefore, lymphangiectasia is the morphological evidence of lymphostasis.23 We determined the number of lymphangiectatic vessels and maximal dilated lymphangiectatic vessel diameter to assess the presence and severity of lymphostasis. Agliano et al. reported an appareance characterized by lymphatic vessels with increased luminal diameter in the dermatochalasis group.15 They found a significantly greater mean lymphatic luminal diameter in the dermatochalasis group compared to the control group; however, although lymphatic vessel density was greater in the DC group, the difference between the DC and control groups did not reach statistical significance. Nagi et al. found significantly greater lymphatic vessel diameter and number of dilated lymphatic vessels compared to the control group.24 In our study, lymphatic vessel density and lympathic vessel diameter were greater in the DC group (p = 0.01, p = 0.02).
Related Knowledge Centers
- Adventitia
- Extracellular Fluid
- Lymph
- Smooth Muscle
- Endothelium
- Lymphatic System
- Capillary
- Circulatory System
- Blood Vessel
- Lymph Capillary