What is the fluid part of the blood that carries nutrients and other substances to cells known as?

The fluid part of the blood that carries nutrients, hormones, antibodies, and waste products to and from cells throughout the body is known as plasma. Plasma makes up about 55% of blood's total volume and serves as the medium for transporting these essential substances. It contains water, electrolytes, proteins, and other components that are crucial for maintaining overall health and facilitating various bodily functions.

Serum, while it is a fluid component of blood, is actually what remains after the blood has clot, and it lacks the clotting factors found in plasma. Hemoglobin is a protein found in red blood cells that is responsible for transporting oxygen, while platelets are cell fragments involved in blood clotting. Therefore, plasma is the correct term for the fluid responsible for nutrient and substance transport within the circulatory system.