what are red blood cells
what are red blood cells

Several substances need to get from one part of the body to another. Such elements are the red blood cells which are an essential component of the blood. Its function is to transport oxygen to body tissues and exchange it for carbon dioxide, which then it carried and eliminated by the lungs.

red blood cells difference
red blood cells difference

What Are Red Blood Cells?

Red blood cells (also called erythrocytes) pick up the oxygen from the lungs and deliver it to the rest of the body. By leaving oxygen, they pick up carbon dioxide – a waste product that must exit the body. With every breath a person takes, oxygen enters the lungs, and carbon dioxide leaves in the process.

One blood cell has a lifetime of about 120 days. Approximately 1% of the erythrocytes renew every day, and the overall amount is over 250 billion cells.



what are red blood cells-production
Image from interactive-biology.com

Production of red blood cells starts in the bone marrow from precursor stem cells. They are released from the bone marrow as immature red blood cells also called reticulocytes, and mature within a day.

Red blood cells consist of 90% hemoglobin. Hemoglobin is a pigment that gives the blood its characteristic red color. A related compound, myoglobin acts as an oxygen store in muscle cells. The function of the red blood cells is to absorb oxygen from the small alveoli found in the lungs and to carry it to all the muscles, tissues and organs of the body.

To achieve this, they must travel through large arteries and small capillaries. Sometimes the capillaries are so small that the red blood cells must be compressed and stretched and even folded to be able to pass and release their oxygen load.

Several nutrients affect the red blood cells and cause their production. Such nutrients which are necessary for their production are iron, Vitamin B12, and folic acid.  A person deficient in one or more of these may have a low red blood cell count.

Shape of Red Blood Cells

shape of red blood cell
image : leavingbio.net

In the case of humans, the red cells have an oval shape, flattened, with a depression in the center. This design is optimized for the exchange of oxygen with the environment that surrounds it.

The cells are flexible so they can pass through the capillaries, where they release the oxygen load. The diameter of a typical erythrocyte is 6-8 μm and is the heaviest particles in the blood.

Red blood cells are the most numerous of all the cells in the blood. An adult body produces 4 to 5 billion red cells per hour. When a red blood cell matures, it expels its nucleus before entering the bloodstream. There are about 30 billion blood cells in an adult. Each cubic millimeter of blood contains between 4.5 and 5.5 million red cells and a total average of 7,500 white cells.

The spleen acts as a reservoir of red blood cells, but its function is somewhat limited in humans. However, in other mammals such as dogs and horses, the spleen releases large amounts of red blood cells at times of stress. Some athletes have tried to use science to exploit this function of the spleen trying to free their reserves of erythrocytes by drugs, but this practice puts the cardiovascular system at risk because it is not prepared to withstand blood whose viscosity is higher than usual.

Diseases Related to Red Blood Cells

Anemia’s are :

  • Conditions characterized by decreased oxygen carrying capacity due to reduced red blood cell count or the concentration of hemoglobin in these cells.
red blood cells anemia
red blood cells anemia
  • Iron-deficiency anemia  is the most common anemia. It occurs when the intake of iron or its absorption in the body decreases, which leads to the reduction in the production of hemoglobin because iron is its main constituent.
  • Sickle cell disease is a genetic disease that results from the mutation of hemoglobin molecules. Turning oxygen of, they become insoluble and lead to changing the shape of red blood cells. These sickle-shaped particles are stiff and can block blood vessels, causing pain, strokes and other tissue damage.
  • Thalassemia is a genetic disorder that results in a change in the quantity produced of hemoglobin subunits.
  • Hemolytic anemia is a group whose cause is anemia due to greater destruction of red blood cells (hemolysis), which can be intrinsic or extrinsic factors origin of red blood cells.
  • Spherocytosis also called hemolytic anemia – Characterized by a genetic defect in the membrane protein and the particle cytoskeleton, leading to small spherical red blood cells (spherocytes). Hence the name, and the fragile constitution, unlike a biconcave and flexible form.
  • The lack of intrinsic factor necessary characterizes pernicious anemia. for the absorption of vitamin B12 from food. Vitamin B12 is essential for the production of hemoglobin.
  • Aplastic anemia (also called Erythropoiesis) – Caused by the inability of the bone marrow to produce particles from the blood
  • The malaria parasite spends part of its life cycle in red blood cells, feeds on hemoglobin and then causes hemolysis, leading to fever. Both sickle cell anemia and thalassemia are common in areas where malaria because these mutations are resistant to this disease.
  • Polycythemias (also called Erythrocytes) – Characterized by an increase in the number of red blood cells. The increase in the viscosity of the blood derived from it can cause various symptoms. In polycythemia, the increase in the primary number of red blood cells comes from a change in the bone marrow.


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