Blood and its components

Blood and its components

 

Respiration, nutrition, defense, regulation ... Blood plays a vital role in many vital functions. It is a living tissue composed of red blood cells, white blood cells and platelets, bathed in a liquid called plasma.

Blood is 55% plasma, 44% red blood cells and 1% white blood cells and platelets

 Blood is life! Pulsed by the heart and circulating in the vessels through the body, oxygen blood nourishes, cleans and defends all the tissues and organs of our body.
Essential functions

Blood carries oxygen, nutrients (sugar, minerals, vitamins ...) and hormones essential to the life of our cells. In return, it evacuates the waste towards the organs of elimination, like the kidneys or the lungs (for the carbon dioxide).

Blood also plays a central role in the body's defense against pathogens (bacteria, viruses ...). And in case of injury, he himself ensures the repair of his vessels (coagulation process).

The blood also carries chemical messengers - the hormones - essential for the regulation and the proper functioning of the body. It helps maintain body temperature and regulate heat throughout the body.

A very organized fabric

Although liquid, blood is a very organized tissue. It is composed of a saline fluid, plasma, in which three types of cells circulate: red blood cells, white blood cells and platelets. For 1 white blood cell, there are about 50 platelets and 1000 red blood cells.

Today, it is not yet possible to make artificial blood. In case of blood loss, there is usually no alternative to transfusion.
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Technical platform, Lille © EFS, Thomas Gogny
Red blood cells: oxygen transporters

The red blood cells transport oxygen from the lungs to the tissues and in return capture the carbon dioxide to evacuate it during the exhalation. These are the most numerous cells in the plasma: about 5 million per mm3 of blood.

Also called erythrocytes or red blood cells, these cells contain a protein, hemoglobin, which is able to fix oxygen and gives blood its red color. Their membrane is bristling with proteins, the antigens, which determine the membership of different blood groups.

A lack of red blood cells - this is called anemia - causes a lot of fatigue. Transfusion of red blood cells may be necessary during severe anemia or severe bleeding.
White blood cells: immune defense specialists

White blood cells (or leukocytes) play a vital role in the defense of the body against external aggression (bacteria, viruses, parasites ...). There are between 4,000 and 10,000 per mm3 of blood.

When a pathogen invades the body, some white blood cells detect it and form specific antibodies against it. Following a donation of blood, the white blood cells are filtered: it is called leukocytes. Indeed, these could lead to adverse effects in the recipient (immunization anti-HLA, chills-hypothermia reaction ...)
Platelets: heal wounds and hemorrhages

Platelets help stop bleeding, prevent or stop bleeding. There are 150,000 to 400,000 per mm3 of blood.

In case of rupture of the wall of a vessel, these tiny cells stick on it and clog the breach. Then, different plasma proteins will reinforce this "plug" thanks to the coagulation process.

Leukemia or chemotherapy treatment can lead to platelet deficiency. Platelet transfusion may also be necessary for some major surgeries.