What makes up more than 55% of blood?

Plasma makes up more than 55% of blood volume, serving as the liquid component that transports various substances throughout the body. It consists primarily of water, but also contains proteins, electrolytes, nutrients, hormones, and waste products. This composition enables plasma to play critical roles in maintaining blood pressure and regulating body temperature, in addition to transporting cells and other essential compounds.

On the other hand, while cells, including red and white blood cells, are crucial for various functions such as oxygen transport and immune response, they collectively account for less than 45% of the total blood volume. Red blood cells, which are responsible for carrying oxygen, and white blood cells, which are involved in the immune response, represent smaller fractions of blood compared to plasma. Thus, understanding the distinction in volume proportions is key to grasping the overall composition of blood.