Library · Physiology
Fluid balance and lymph
Make it clearer
In any tissue there is always some extra fluid between the cells. It is called interstitial fluid, and if it stayed there it would build up. It does not stay: the lymphatic vessels reabsorb it and return it to the blood.
That fluid does not enter the lymphatic vessel because a pump sucks it in. It enters because of an imbalance in pressure between the interstitium and the capillary itself: hydrostatic pressure, which pushes, and oncotic pressure, which holds fluid back with dissolved proteins.
The volume it moves is not small: eight to twelve liters a day. And it moves it without a heart. Two thirds of that resting flow comes from its own pump, made of pericytes, contractile cells that wrap around the vessel, and of valves that let fluid through in only one direction.
Picture a small pump working on its own, and the muscle that helps it every time you move.
In brief
The lymphatic system keeps fluid in balance: its vessels reabsorb the excess in the tissues, keeping it from building up, and return it to the blood.
That fluid enters the lymphatic capillary because of the imbalance between hydrostatic and oncotic pressure.
The system moves eight to twelve liters a day: two thirds of the resting flow comes from its own pump of pericytes and valves, and the rest from skeletal muscle compression.
A small pump working on its own, helped by muscle whenever you move.
Sources (2)
- National Center for Biotechnology Information, StatPearls PublishingPhysiology, Lymphatic System, StatPearlsPublished
- National Center for Biotechnology Information, StatPearls PublishingAnatomy, Lymphatic System, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
Updated