What is the main function of red blood cells?
Do you know what cells are the most abundant in the bloodstream? If you do, you also know that these small red biconcave discs contain hemoglobin and actually carry oxygen through our veins. In organisms of some animals hemoglobin might be found in its free state but in a human body it is always contained in a "jacket" known as the red blood cell. It's obvious that various characteristics of these red blood cells such as shape, size or quantity influence greatly the capacity of blood to carry oxygen .
A red blood cell also has a peculiar "super power" of becoming distorted in order to squeeze through small capillaries and then to restore to its original shape.