1. Oxygen transport: Red blood cells transport oxygen as oxyhemoglobin.
2. Carbon Dioxide: Red blood cells transport carbon dioxide as carbaminohemoglobin.
3. Bile production: Red blood cells change to produce bilirubin and biliverdin.
4. Viscosity: It maintains blood density and viscosity.
5. Maintain acid-base balance: Red blood cells maintain acid-base balance in the body.
6. Blood Grouping: It has plasma membrane antigen proteins which are responsible for blood grouping.
7. Nitric oxide production: Red blood cells produce nitric oxide. Nitric oxide is used in endothelial cells like L-arginine.
8. Constriction of blood vessels: Red blood cells produce hydrogen sulphide. Hydrogen sulfide signals the constriction of blood vessels.