Placeholder Image

字幕列表 影片播放

已審核 字幕已審核
  • In a nutshell, the lymphatic system is a drainage system that removes excess fluid from body tissues and returns it to the bloodstream.


  • It's actually a subsystem of both the circulatory and immune system.


  • The major purpose of the circulatory system is to bring oxygen and nutrients to body tissues and remove wastes.


  • This exchange happens in the smallest blood vessels called the capillaries.


  • Blood plasma containing nutrients moves out of capillaries at the arterial end of capillary beds, while tissue fluid containing wastes re-absorbs back in at the venous end.


  • However, not all of the fluid is drawn back to the bloodstream at this point.


  • About 15% of it is left in the tissues and would cause swelling if accumulated.

    約有 15% 殘留在組織內,持續積聚會引起腫脹。

  • This is where the lymphatic system comes into play. It picks up the excess fluid and returns it to the circulatory system.


  • Unlike the blood circulatory system, which is a closed loop, the lymphatic system is a one-direction, open-ended network of vessels.


  • Lymphatic vessels begin as lymphatic capillaries made of overlapping endothelial cells.


  • The overlapping flaps function as a one-way valve.


  • When fluid accumulates in the tissue, interstitial pressure increases, pushing the flaps inward, opening the gaps between cells, allowing fluid to flow in.


  • As pressure inside the capillary increases, the endothelial cells are pressed outward, closing the gaps, thus preventing backflow.


  • Unlike blood capillaries, the gaps in lymphatic capillaries are so large that they allow bacteria, immune cells, such as macrophages, and other large particles to enter.


  • This makes the lymphatic system a useful way for large particles to reach the bloodstream.


  • It is used, for example, for dietary fat absorption in the intestine.


  • Once inside lymphatic vessels, the recovered fluid is called lymph.


  • Lymph flow is enabled by the same forces that facilitate blood flow in the veins.


  • It goes from lymphatic capillaries to larger and larger lymphatic vessels and eventually drains into the bloodstream via the subclavian veins.


  • On the way, it passes through a number of lymph nodes, which serve as filters, cleansing the fluid before it reaches the bloodstream.


  • Lymph nodes are small bean-shaped structures scattered throughout the lymphatic network.


  • They are most prominent in the areas where the vessels converge.


  • Lymph nodes contain macrophages and dendritic cells that directly swallow up any pathogens, such as bacteria or viruses, that may have been taken up from an infected tissue.


  • They also contain lymphocytes: T-cells and B-cells, which are involved in adaptive immune response, a process that produces activated lymphocytes and antibodies specific to the invading pathogen.

    它們也含有淋巴細胞:T 細胞和 B 細胞,主要負責適應性免疫反應,促進淋巴細胞和入侵病原體的抗體的活化。

  • These are then carried by the lymph to the bloodstream to be distributed wherever they are needed.


  • The lymphatic system also includes lymphoid organs.


  • Primary lymphoid organs, the thymus and bone marrow, are the sites of lymphocyte production, maturation and selection.


  • Selection is the process in which lymphocytes learn to distinguish between self and non-self, so they can recognize and destroy pathogens without attacking the body's own cells.


  • Mature lymphocytes then leave the primary for the secondary lymphoid organs, the lymph nodes, spleen, and lymphoid nodules, where they encounter pathogens and become activated.


In a nutshell, the lymphatic system is a drainage system that removes excess fluid from body tissues and returns it to the bloodstream.


已審核 字幕已審核

單字即點即查 點擊單字可以查詢單字解釋

C1 高級 中文 美國腔

淋巴系統是怎麼運作的?一起來認識吧!(The Lymphatic System Overview)

  • 8809 88
    Amy.Lin 發佈於 2023 年 07 月 26 日