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 be used for blood transfusions. Several blood tests involve red blood cells. These include a "RBC count" (the number of red blood cells per volume of blood), calculation of the hematocrit (percentage of blood volume occupied by red blood cells), and the erythrocyte sedimentation rate. The blood type needs to be determined to prepare for a blood transfusion or an organ transplantation. Many diseases involving red blood cells are diagnosed with a blood film (or peripheral blood smear), where a thin layer of blood is smeared on a microscope slide. This may reveal abnormalities of red blood cell shape and