Red blood cells - the cells that help you breath

Adult humans carry around 5 liters of blood in their circulatory system. Roughly half of that is cells, and the other half is a pale yellow liquid called plasma. The vast majority of these cells are erythrocytes, more commonly known as red blood cells (RBCs). Our red blood cells are the most abundant cell type in the human body accounting for approximately 70% of all your cells. They measure roughly 7 microns in diameter and around 1-2 microns in thickness.