Lymphatic System

A primary function of the **lymphatic system** is to drain excess fluid from tissues and return it to the bloodstream through a network of vessels, trunks and ducts. Lymphatic vessels start as open-ended capillaries, which feed into progressively larger lymphatic vessels. Along this pathway, lymph passes through lymph nodes, which are commonly located in the groin, armpits, neck, chest and abdomen. Lymphatic vessels in the arms and legs convey lymph to larger lymphatic vessels in the torso. Unlike blood, lymph is not actively pumped by the heart; rather, it is forced through the vessels by body movements, skeletal muscle contractions and breathing. One-way valves (semi-lunar valves) in lymphatic vessels ensure that lymph flows consistently toward the heart. Lymph travels from the lymphatic capillaries to larger lymphatic vessels and eventually enters the circulatory system through lymphatic ducts located at the junction of the jugular and subclavian veins in the neck. *LICENSES AND ATTRIBUTIONS CC licensed content, Shared previously, Donna Browne, Immune System Module 1: Anatomy of the Lymphatic and Immune Systems, Authored by: OpenStax College. License: CC BY: Attribution. License Terms: Download for free at:http://cnx.org/contents/XuVQoXkr@1/Immune-System-Module-1--Anatom* ## Keywords lymphatic system lymph sap flow tonsils thymus blood vessel capillaries inguinal lymph nodes thoracic spleen axillary