Physiology of marathons amounts of blood to and from the lungs to reach all bodily tissues is dependent on having a high cardiac output along with sufficient levels of total body hemoglobin. Hemoglobin is the oxygen carrying protein within blood cells that allows for the proper transportation of oxygen from the lungs to other bodily tissues via the circulatory system. In order for the transportation of oxygen in blood to be effective during a marathon, the distribution of blood needs to be equally efficient in order for a marathoner's oxygen demands to be met during a race. The mechanism that allows for this
Red blood cell loss, such as prior to an operation. Before blood is given, a small sample of the recipient's blood is tested with the transfusion in a process known as cross-matching. In addition to the transmission of infection, certain types of transfusion reaction. In 2008 it was reported that human embryonic stem cells had been successfully coaxed into becoming red blood cells in the lab. The difficult step was to induce the cells to eject their nucleus; this was achieved by growing the cells on stromal cells from the bone marrow. It is hoped that these artificial red blood cells can eventually