What is the primary function of plasma in the blood?

The primary function of plasma in the blood is to transport nutrients and waste. Plasma is the liquid component of blood, making up approximately 55% of its volume, and serves as a medium through which various substances are dissolved and transported throughout the body. It carries essential nutrients such as glucose, amino acids, and vitamins from the digestive system to the cells, while also helping to transport metabolic waste products like urea and carbon dioxide to excretory organs such as the kidneys and lungs for removal from the body.

While plasma does play a role in other functions such as carrying hormones and proteins, its primary role revolves around transportation. The other options refer to functions performed by various blood components beyond plasma: red blood cells are responsible for oxygen transport, white blood cells defend against infections, and the body's ability to regulate temperature involves various physiological mechanisms, including the functions of blood flow and sweat production, rather than being solely reliant on plasma.