Erytrosyyttejä

Erytrosyyttejä, known in English as erythrocytes or red blood cells, are the most common type of blood cell and the vertebrate's primary means of delivering oxygen (O2) to the body tissues—via blood flow through the circulatory system. They take up oxygen in the lungs or gills and discharge it in tissues as they pass through the body. The counterpart of this is they carry away most of the carbon dioxide, a waste product, to the lungs or gills to be eliminated from the body.

Erythrocytes are typically biconcave discs, meaning they are flattened discs that are indented on both sides. This shape increases their surface area, facilitating the diffusion of oxygen and carbon dioxide. They lack a nucleus and most other organelles in their mature state, which maximizes the space available for hemoglobin, the protein responsible for oxygen transport. Hemoglobin contains iron, which binds to oxygen in oxygen-rich areas like the lungs and releases it in oxygen-poor areas like active tissues.

The production of erythrocytes, known as erythropoiesis, occurs in the bone marrow. This process is regulated by erythropoietin, a hormone produced primarily by the kidneys in response to low oxygen levels in the blood. The lifespan of an erythrocyte is typically around 120 days, after which they are removed from circulation by macrophages, mainly in the spleen and liver. The breakdown products of erythrocytes, particularly iron, are recycled for new red blood cell production. Anemia is a condition characterized by a deficiency of erythrocytes or hemoglobin, leading to reduced oxygen-carrying capacity of the blood.