A complete blood count is a measure of the various cells within the blood. Red blood cells and hemoglobin are responsible for carrying oxygen to the body and carbon dioxide out of the body. The red blood cell count is the absolute number of red blood cells in the blood. Hemoglobin is the part of the red blood cell that attaches to oxygen and carries it throughout the body.
Hematocrit is the percentage of blood that comprises red blood cells. The mean corpuscular volume is the average amount of space occupied within each red blood cell. The mean corpuscular hemoglobin is an estimate of the amount of hemoglobin carried by each red blood cell. The mean corpuscular hemoglobin concentration is an estimate of the level of hemoglobin in a given number of red blood cells. The red blood cell distribution width measures the variability in size of the red blood cells.
White blood cells are part of the immune system and there are several types of white blood cells including neutrophils, lymphocytes, monocytes, eosinophils and basophils.
Platelets are involved in the process of blood clotting. When a blood vessel is damaged, platelets clump together and help to initiate clotting.