What term describes the fluid medium that carries blood cells?

The term that describes the fluid medium carrying blood cells is plasma. Plasma is a yellowish liquid component of blood that makes up about 55% of its overall composition. It is primarily composed of water, but it also contains proteins, electrolytes, nutrients, hormones, and waste products. Plasma plays a crucial role in transporting blood cells, nutrients, and other substances throughout the body, ensuring that cells receive the necessary components for function and that waste products are removed efficiently.

Serum, while also a component of blood, is the liquid that remains after blood has clotted and does not contain clotting factors. Lymph is a fluid found in the lymphatic system, which helps in immune functions and fat absorption but does not carry blood cells. Interstitial fluid surrounds cells and is found in the spaces between them, playing a role in the exchange of substances between blood and tissues, but it is not responsible for carrying blood cells themselves. Thus, plasma is the correct term for the fluid medium carrying blood cells.