Erythrocyte
Red blood cell, in humans a seedless cell. Mainly contains the blood pigment haemoglobin, which serves to transport oxygen with the cardiovascular system.
The deformability and the number of erythrocytes in the volume unit determine significantly the fluidity of the blood and thus its flow resistance. We find an average of 5.1 million erythrocytes per ml of blood in men and 4.6 million in women. Changes in the erythrocyte count usually correspond to those of haemoglobin.
Erythrocytes only have a lifespan of 100-120 days and are constantly regenerated in the red bone marrow. The red blood cells (erythrocytes, singular:erythrocyte; from the Greek erythros for "red" and kytos for "hollow" or "cell") are the most common cells in the blood of vertebrates. They're also called red blood cells. They appear under the microscope as approximately equally large, pale, round discs, which are slightly dented in the middle from both sides (biconcave). They are between 7 and 8 µm in size and thus partly smaller than the capillaries they pass through. As a result, they lie close to the endothelium of the capillary and can release oxygen to the tissue and absorb carbon dioxide. Due to their special shape, they are able to walk through even capillaries that are only half the size.