The erythrocyte deformability or flexibility of the red blood cells enables the cells to pass different lumen vessels. In addition, erythrocytes change their shape depending on the temperature and flow rate of the blood, thereby changing the blood viscosity at the same time. Erythrocytes, for example, are considered abnormal in the context of globular or sickle cell anemia.

What is the erythrocyte deformability?

The erythrocyte deformability or flexibility of the red blood cells enables the cells to pass different lumen vessels.

The red blood cells are also called erythrocytes. The blood cells contain the so-called hemoglobin and are thus responsible for the transport of oxygen in the human body. Oxygen is needed by all body tissues for survival. In the lungs, oxygen enters the blood where it is unbound and bound.

Between oxygen and hemoglobin of the red blood cells there is binding affinity in the environment of the lungs. Bound to the red blood cells, the oxygen travels with the blood to all areas of the human body. Because the environment gradually changes as it travels through the body, reducing the binding affinity, oxygen is eventually released and absorbed by the target tissues.

The erythrocyte deformability is one of the most important properties of red blood cells. Because of their flexibility, the erythrocytes are able to pass through the blood of the narrowest vessels and to pass through the small-lumen capillaries. This phenomenon is particularly relevant to the oxygenation of all body tissues. The deformability of the erythrocyte membrane thus allows the passage of red blood cells through thinnest pores. With each change in the shape of the erythrocytes, the flow property and the viscosity of the blood change.

Function & Task

The shape of the red blood cells increases their surface area, thereby enabling improved gas exchange. Due to their high flexibility, erythrocytes can also migrate through capillaries that are smaller in diameter than the erythrocytes themselves. Especially when narrow capillaries pass, erythrocytes become deformed or, in the context of pseudoagglutination, assemble into rouleaux.

Under the cell membrane of the red blood corpuscles is an einstrahlendes network of structuring and densely arranged filaments, which is referred to as erythocytic cytoskeleton and serves to maintain a biconcave shape. Proteins such as spectrin and ankyrin are essential components of the cells and contribute to their deformability. Apart from their typically biconcave shape, erythrocytes can take on a different shape thanks to their flexibility.

In their basic form, the red blood cells are called discyocytes. This biconcave disc shape takes up the blood cells in flowing blood. However, there are several dozen different shape variants. In narrower capillaries, for example, the cells become stomatocytes and, in this context, are in folded cup form, facilitating the passage of narrow-lumen capillaries. Dacryocytes, on the other hand, are tear-shaped, and echinocytes are sting-like erythrocytes, as occur in hypertonic solutions.

The flexibility of the erythrocytes affects proportionately above all the blood viscosity. This refers to the viscosity of the blood, which combines the material properties with the properties of liquids. Due to its viscosity, the blood shows an adapted flow behavior and does not behave like a Newtonian fluid. Its flow behavior is not proportional, but erratic. In addition to the Fåhraeus-Lindqvist effect, hematocrit, temperature and flow velocity are responsible for this.

A major role in this context is the erythrocyte deformability including erythrocyte aggregation. These relationships allow the blood to take on different flow behavior in different areas of the body and prevent the clumping of cellular blood components. At low flow velocity in the blood, erythrocytes attach to each other and form chains. This rollover or agglomeration is to some extent physiological.

Diseases & complaints

In the context of various diseases, the deformability of the erythrocytes is impaired. In yet other diseases of the blood system, the red blood cells are in abnormal form variants. Any abnormality of the erythrocyte form or its deformability has an effect on the blood viscosity and can therefore have serious consequences. In the form of the so-called acanthocytes, the red blood cells are present as spiny cells, for example. Erythrocytes take on this shape, for example, in disorders of phospholipid metabolism.

Anulocytes are again annular erythrocytes, as they are in high grade anemias. In the form of fragmentocytes, erythrocytes occur in the phenomenon of intravascular hemolysis. Macrocytes are also a pathological variant of red blood cells. The erythrocytes are greatly enlarged, as it may be the case for example in the context of folic acid deficiency. Also in megaloblastic anemia, the red blood cells are present in an enlarged form. This form variant is called megalocyte. A reduction to the so-called microcyte experience the blood components in iron deficiency diseases and hemoglobin deficiency diseases.

One of the best-known form diseases of erythrocytes is the ball cell anemia, in which the red blood cells appear as globularly small microsphere cells. Similarly known as the Kugelzellemia is sickle cell anemia. The red blood cells change their physiological form in the context of this disease to sickle shape, the so-called sickle cell.

In the context of iron deficiency, pernicious anemia and bone marrow lesions, the cells in turn adopt the abnormal shape of the poikilocytes. As target cells, the red blood cells are in the context of thalassemia, toxic anemia or iron deficiency anemia. This form variant is characterized by the annular arrangement of hemoglobin.

Even after mechanical damage, the erythrocytes change their shape to an abnormal shape: the so-called schistocytes. These are deformed erythrocytes, which are ultimately just a fragment of red blood cells. An increased erythrocyte monolayer reveals inflammatory phenomena in immune complex diseases.

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