Here's why:

* Plasma makes up about 55% of the total blood volume. It's a straw-colored liquid that contains water, proteins, electrolytes, nutrients, and waste products.

* Red blood cells (erythrocytes) are the second largest component, carrying oxygen throughout the body. They make up about 45% of blood volume.

* White blood cells (leukocytes) and platelets make up a very small percentage of the blood volume, but they are crucial for fighting infections and clotting blood.