lymphatic system

(noun)

in mammals, including humans, a network of lymph vessels and lymph nodes that transport fluid, fats, proteins, and lymphocytes to the bloodstream as lymph, and remove microorganisms and other debris from tissues

Related Terms

Examples of lymphatic system in the following topics:

  • Structure of the Lymphatic System

    • The lymphatic system consists of lymphatic vessels and associated lymphoid organs.
    • The structure of the lymphatic system facilitates these general roles.
    • The lymphatic vessels are the lymphatic system equivalent to the blood vessels of the circulatory system and drains fluid from the circulatory system.
    • Lymphatic organs are the site of many important functions for the immune system.
    • Describe how the lymphatic system consists of lymphatic vessels and associated lymphoid organs

  • Functions of the Lymphatic System

    • The lymphatic system is the site of many key immune system functions.
    • It is important to distinguish that immune system functions can happen almost anywhere in the body, while the lymphatic system is its own system where many immune system functions take place.
    • One of the main functions of the lymphatic system is to drain the excess interstitial fluid that accumulates.
    • The lymphatic system also facilitates fatty acid absorption from the digestive system.
    • In addition to the tissue fluid homeostasis, the lymphatic system serves as a conduit for transport of many cells that involved in immune system function.

  • Distribution of Lymphatic Vessels

    • The lymphatic system comprises a network of conduits called lymphatic vessels that carry lymph unidirectionally towards the heart.
    • The lymphatic system is a circulatory system for lymphatic fluid, comprising a network of conduits called lymphatic vessels that carry a lymphatic fluid, in one direction towards the heart.
    • The lymphatic system is composed of many different types of lymph vessels over a wide distribution.
    • Due to this fact, the lymphatic system as a whole is a not a closed system that has linear flow, while the cardiovascular system is a closed system with true circular flow.
    • Describe the structure of the lymphatic system and its role in the immune system and blood circulation

  • Lymph Trunks and Ducts

    • After filtration by the lymph nodes, efferent lymphatic vessels take lymph to the end of the lymphatic system.
    • The final goal of the lymphatic system is to recirculate lymph fluid back into the plasma of the bloodstream.
    • There are two specialized lymphatic structures at the end of the lymphatic system, which are called the lymph trunks and ducts.
    • Lymphatic trunks then drain lymph fluid into the lymph ducts, which are the final part of the lymphatic system.
    • Reaching this point marks the end of lymph fluid's journey through the lymphatic system.

  • Metastasis Through Lymphatic Vessels

    • Some cancer cells acquire the ability to penetrate the walls of lymphatic and/or blood vessels, after which they are able to circulate through the bloodstream (circulating tumor cells) to other sites and tissues in the body.
    • This process is known as a lymphatic or hematogeneous spread.
    • Metastasis is a complex series of steps in which cancer cells leave the original tumor site and migrate to other parts of the body via the bloodstream or the lymphatic system.
    • By degrading the ECM, which acts as a barrier to adjoining tissue, cancer cells are able to breach the ECM and enter the lymphatic system.
    • Lymphatic spread: Invasion into the lymphatic system allows the transport of tumor cells to regional and distant lymph nodes and, ultimately, to other parts of the body.

  • Lymphatic Vessel Structure

    • The general structure of lymphatic vessels are similar to that of blood vessels.
    • This is largely because blood vessels and lymphatic vessels are the two types of vessels in the body.
    • The smallest vessels, such as the lymphatic capillaries even lack the outer adventitia altogether.
    • A lymphagion is the term for the space between two semilunar valves in a lymphatic vessel, and represents a functional unit of the lymphatic system.
    • Without valves, the lymphatic system would not be able to function without a central pump, because the smooth muscle contractions only cause smaller changes in pressure and volume within the lumen of the lymph vessels, and the fluid would just move backwards when the pressure dropped.

  • Lymphoid Tissue

    • The tissues of lymphoid organs are different than the tissues in most other organ systems because different tissues within the system vary considerably based on cell cycle proliferation of lymphocytes.
    • Lymphatic tissues begin to develop by the end of the fifth week of embryonic development.
    • Lymphatic vessels develop from lymph sacs that arise from developing veins, which are derived from mesoderm, the inner tissue layer of the embryo.
    • Development of lymphatic tissue starts when venous endothelial tissues differentiate into the lymphatic endothelial tissues.
    • Smaller lymph vessels and lymphatic capillaries develop after that until the lymphatic system is completed at the closed end of every lymphatic capillary.

  • Lymphatic Capillaries

    • Lymphatic circulation begins in the smallest type of lymph vessels, which are the lymph capillaries.
    • Unlike larger lymphatic vessels, lymphatic capillaries do not contain smooth muscle, nor do they have a well developed adventita, only small elastic filaments that perform a similar function to adventitia.
    • During lymph vessel obstruction (such as through elephantiasis infection), lymph will be unable to progress normally through the lymphatic system, and pressure within the blocked off lymph capillaries will increase to the point where backflow into the tissues may occur, while the pressure of intersitial fluid gradually rises.
    • The other function of the lymphatic capillaries is to bring lymph further into the lymphatic vessels.
    • Collecting vessels are the vessels where multiple capillaries converge, which are where the internal valves and smooth muscle start to appear, which moves lymph further along the system despite the fall in pressure that occurs when moving from the higher pressure capillaries to the lower pressure collecting vessels.

  • Lymph Nodes

    • Lymph nodes are small oval-shaped balls of lymphatic tissue, distributed widely throughout the body and linked by lymphatic vessels.
    • Lymph nodes are small oval-shaped balls of lymphatic tissue, distributed widely throughout the body and linked by a vast network of lymphatic vessels.
    • Lymph nodes are repositories of B cells, T cells, and other immune system cells, such as dendritic cells and macrophages.
    • Molecules found on bacteria cell walls, or the cell walls of virally infected cells or even chemical substances and toxins secreted from bacteria, called antigens, may be taken up by cells into the lymph system and then into lymph nodes.
    • This diagram shows the network of lymph nodes and connecting lymphatic vessels in the human body.

  • Lymphatic Tissue Development

    • Lymphatic tissue development begins by the end of the fifth week of embryonic development.
    • Lymphatic tissues begin to develop by the end of the fifth week of embryonic development.
    • Lymphatic vessels develop from lymph sacs that arise from developing veins, which are derived from mesoderm.
    • From the jugular lymph sacs, lymphatic capillary plexuses spread to the thorax, upper limbs, neck, and head.
    • Some of the plexuses enlarge and form lymphatic vessels in their respective regions.