The lymphatic system – formation and removal of tissue fluid

The human lymphatic system has the task of removing all substances from the connective tissue which cannot be removed by the blood vessel system (so-called obligatory lymph load). Without a functioning lymphatic system, humans are not viable.

In this first part about the human lymphatic system, you will learn how tissue fluid is formed and degraded.


Formation of tissue fluid (GB)

The formation of tissue fluid (GB) takes place through the following three processes:

1.1. Filtration and reabsorption

Filtration describes the release of ultrafiltrate (UF) from the blood capillary into the surrounding tissue.

1.2. Cytopempsis

Cytopempsis is the vesicular protein transport through the endothelial cell of the blood capillary from the blood into the tissue. The protein has a carrier function for e.g. fat-soluble vitamins.

Once the transported substances have been released into the surrounding tissue, the protein is useless and can only be removed via the lymphatic system.

Anatomy HumanIf the plasma proteins in the tissue (interstitium) are present, they promote filtration. Conversely, they increase reabsorption if they occur in the blood capillary.

Blood wall pressure (BWD) + proteins (in tissue) ⇒ Filtration increased.
plasma proteins (blood capillary) + tissue pressure ⇒ reabsorption increased.

Tissue fluid is ultrafiltrate and proteins that have entered tissue through cytopempsis.


1.3. Diffusion

Diffusion (lat. dispersion) is a natural process, takes place without energy supply and uses the movement of the molecules. The aim is the complete and uniform mixing of two or more substances. In the human body, diffusion is unusable for longer distances.


Diffusion distance in relation to diffusion time

Distance Time
X X2
3 9
10 100
  1. The diffusion occurs equally in both directions (up to 70,000 l per day!).
  2. The physiological diffusion path in the body is < as 1/10 mm
  3. Edema causes the tissue cells to move away from each other and the diffusion distance increases.
  4. This worsens the nutritional status of the cells.
Diffusion through a semipermeable membrane is called osmosis.


Degradation of Tissue Fluid (GA)

The breakdown of the tissue fluid takes place through the following processes:

2.1. Reabsorption

Reabsorption is the reabsorption of ultrafiltrate (UF) into the blood. This is done by hydration via the plasma proteins in the capillary (hydration is the ability to bind water to itself). The difference between filtration and reabsorption (approx. 10 % of the ultrafiltrate) is disposed of via the lymphatic system.

If filtration is greater than reabsorption, UFue edema occurs (e.g. right heart failure or venous congestion). If the reabsorption is smaller than the filtration, a UFue edema also develops (too few proteins due to e.g. hunger or increased excretion in intestinal or kidney disease = hypoproteinemia).

2.2. Diffusion

See point 1.3.

2.3. Lymphodynamics

Here, what is not removed via the blood capillaries is removed. This is also called the lymph load.

Obligate lymphatic loads:

  • Protein
  • Fat
  • cells (e.g. after trauma)

Facult lymphoid loads:

  • Water

This post is also available in: German

William C. Hilberg
As an author, Mr. Hilberg has published several papers on health issues that have gained international recognition. He is close to nature and loves the seclusion and activity as a freelance journalist. In his function as editor William C. Hilberg manages the entire content of PENP. Our team greatly appreciates his expertise and is proud to have him on board.