INTRODUCTIONS Blood is a fluid connective tissue that circulated around the body. Blood is primarily used to transport medium for the maintenance of homeostasis (Mader, 2010). Blood transports oxygen and carbon dioxide, nutrients and wastes, metabolic substrates and hormones between organs and tissues. Blood also involves in defending against the pathogens and infections, and blood loss. Blood helps to regulate the body heat, maintain its own water-salt balance, and provides a buffer for acid-base balance. Blood consists of formed elements including erythrocytes (red blood cells), leukocytes (white blood cells), and platelets that are suspended in plasma (Sherwood, 2012). Blood cells are produced in the red bone marrow from the undifferentiated…show more content… The buffy coat on above the packed red blood volume contain white blood cells and platelets. Plasma have the most percentage in the total blood volume. The kidney produced erythropoietin hormones that stimulates the production of red blood cells in the red bone marrow known as the erythropoiesis process (Mader, 2010). Erythrocytes (red blood cells) are essentially for transport oxygen and carbon dioxide for gas exchange. Red blood cells are lack of nucleus. They contain the hemoglobin which mainly bind to oxygen to transport it to tissues. The red blood cells have the average life span of 120 days and destructive by the spleen and liver. The degraded haemoglobin, iron, and bilirubin are recycled. Nutrients such as vitamin B12, folic acid, and iron are required for the erythropoiesis. Leukocytes or white blood cells have a nucleus and either granular or a-granular (Mader, 2010). Leukocytes are translucent and observed through staining. The granular leukocytes are neutrophils, basophils, and eosinophils. Neutrophils are neutral or no dye color and have more than 3 lobes nucleus (Sherwood, 2012). Eosinophils have the affinity of the red dye eosin and basophils is observed to have the blue dye.