Red blood cell, also called erythrocyte, cellular component of blood, millions of which in the circulation of vertebrates give the blood its characteristic colour and carry oxygen from the lungs to the tissues. The mature human red blood cell is small, round, and biconcave; it appears dumbbell-shaped in profile.
Just so, what is the shape of a human red blood cell?
The shape of a red blood cell is a biconcave disk with a flattened center - in other words, both faces of the disc have shallow bowl-like indentations (a red blood cell looks like a donut). Production of red blood cells is controlled by erythropoietin, a hormone produced primarily by the kidneys.
How does the shape of a red blood cell contribute to its function?
Its biconcave shape maximises the surface area to increase efficiency of oxygen absorption. Its shape also allows it to ''squeeze'' through narrow vessels and can enter even the thinnest capillaries around the body. Red blood cells do not have a nucleus, which again increase the oxygen capacity.