Final answer:
The heavy formed elements of blood, primarily erythrocytes, make up about 45% of the blood volume, with leukocytes and platelets accounting for less than 1%.
Step-by-step explanation:
The formed elements of blood consist of erythrocytes (red blood cells), leukocytes (white blood cells), and platelets. When blood is centrifuged, these elements separate based on density, with erythrocytes being the heaviest and settling at the bottom. The volume of erythrocytes, also known as packed cell volume (PCV) or hematocrit, is normally about 45% of the blood. This percentage can vary depending on factors such as gender, with normal hematocrit values ranging from 37 to 47 for females (average value of 41) and from 42 to 52 for males (average value of 47). Leukocytes and platelets make up less than 1% of the blood and are not usually considered in hematocrit measurements. Therefore, the heavy formed elements, which are primarily erythrocytes, constitute approximately 45% of the blood volume.