Are blood platelets different from red blood cells?

The blood: blood plasma and blood cells

blood On closer inspection, it turns out to be a mixture of hundreds of substances with diverse tasks.

The normal amount of blood in adults is just under 1/13 of the body weight, i.e. 5–7 liters. About 55% of this is liquid blood plasma and 45% is solid blood cells.

The various components of the blood, i.e. the blood cells, consisting of red blood cells, white blood cells and platelets, as well as the blood plasma, consisting of water, blood proteins and other substances such as vitamins, blood sugar (glucose), creatinine, urea and electrolytes (dissolved salts)., Michael Amarotico, Munich

Blood plasma

The liquid, yellowish one Blood plasma consists of 90% water. Around 100 different proteins are dissolved in it:

  • This is the main protein Albumin. In terms of quantity, it is the most important transport protein. Albumin also holds the water in the blood vessels.
  • In second place are those Globulins. The globulinsAlpha- and beta globulins primarily have a transport function, Gamma globulins however are Antibody, Soluble antibodies circulating in the blood and tissues that recognize pathogens and can render them harmless. Because the gamma globulins play a central role in the immune system, they are also called immunoglobulins.
  • In terms of quantity, it is small, but essential for blood clotting Fibrinogen. Is called blood plasma without fibrinogen Blood serum.

The blood plasma also contains blood sugar (more precisely glucose), fats and other nutrients, salts, vitamins, hormones and metabolic products.

Blood cells

The solid components of the blood are called Blood cells or called blood cells.

  • The disc-shaped red blood cells (Erythrocytes) transport with the help of their red blood pigment (Hemoglobin) the vital oxygen from the lungs to the whole body.
  • The white blood cells (Leukocytes) perform key functions in the defense against pathogens. They are divided into monocytes, lymphocytes and various granulocytes.
  • The Platelets, also called platelets, are an important part of blood clotting. Excessive clumping of platelets can lead to thrombosis.

All blood cells are made in the bone marrow. There are Blood stem cells (haematopoietic stem cells) that divide throughout life and develop into various blood cells. This blood cell development is through various Blood formation growth factors stimulated, some of which can also be produced industrially.

Mainly used at the moment Erythropoietin (e.g. ERYPO®) in certain forms of anemia and G-CSF (Granulocyte colony-stimulating factor: e.g. Neupogen®, Granocyte®) in the case of granulocyte deficiency.

Erythropoietin is normally made in the kidney and stimulates the production of red blood cells in the bone marrow. A lack of oxygen is an important stimulus to produce more erythropoietin. With impaired kidney function, the erythropoietin production decreases, so that anemia develops. In patients with chronic kidney disease, subcutaneous or intravenous administration of artificially produced erythropoietin can prevent anemia, thus avoiding frequent blood transfusions.

G-CSF. If there is a pronounced leukocyte deficiency due to disease or chemotherapy, the risk of life-threatening infections is high. G-CSF (given subcutaneously) shortens the time until the bone marrow can produce enough granulocytes again. It has no effect on the formation of red blood cells.

After they mature, the blood cells in the bone marrow are flushed into the bloodstream, which they use to circulate around the body. All blood cells have a limited lifespan, for example that of red blood cells is around 120 days. Then they are "worn out" (can no longer squeeze through the smallest vessels) and get stuck in the spleen, where they are then broken down.


Dr. med. Nicole Menche, Dr. med. Arne Schäffler in: Gesundheit heute, edited by Dr. med. Arne Schäffler. Trias, Stuttgart, 3rd edition (2014). Revision and update: Dr. med. Sonja Kempinski | last changed on at 12:57