Lümfisooni

Lümfisooni is the term used in Estonian medical language to denote a lymphatic vessel, one of the conduits in the lymphatic system that transports lymph, a fluid derived from interstitial tissue fluid, back toward the venous circulation. Lymphatic vessels form a network that begins with closed-ended lymphatic capillaries in nearly all tissues and progresses into larger collecting lymphatics that travel with arteries and veins to drain into the venous system via the thoracic duct or the right lymphatic duct.

Structure and distribution: Lymphatic capillaries are thin-walled, highly permeable vessels that absorb interstitial fluid, proteins, and immune cells. They feed into collecting lymphatics, which have thicker walls containing smooth muscle and one-way valves to maintain unidirectional flow. Collecting vessels group into larger trunks and eventually channel lymph to the venous system at the junctions of the internal jugular and subclavian veins on the left (through the thoracic duct) and the right (through the right lymphatic duct).

Function: Lümfisooni participate in fluid homeostasis by returning excess interstitial fluid to the bloodstream, aid in immune surveillance by transporting lymphocytes and antigen-presenting cells, and, in the gut, help absorb dietary fats via specialized intestinal lacteals.

Clinical relevance: Impairment or obstruction of lymphatic flow can cause lymphedema, infections, or impaired immune responses. Imaging and lymphatic mapping (such as lymphangiography or ultrasound) are used to assess lymphatic function, particularly before surgical procedures or in cancer staging, since lymphatic routes can serve as pathways for metastasis.