How does blood deliver oxygen to cells of the body?
Red Blood Cells
Red Blood cells circulate the entire body system to carry oxygen to all parts of the body. These red blood cells are concave on each side and contain a substance called Hemoglobin which is a compound if iron. Hemoglobin combines really well oxygen from the air. When haemoglobin combines with oxygen it turns bright red. Hence the reason why you cut yourself blood is red-The haemoglobin is always combining with oxygen from the air