Final answer:
The fluid called plasma circulates through the blood system, carrying blood cells and various substances throughout the body, aiding in homeostasis and providing a medium for cellular transport.
Step-by-step explanation:
The fluid that circulates through the blood system via muscular contractions is called plasma. Plasma is the clear, straw-colored liquid portion of blood that carries water, proteins, salts, lipids, glucose, and the blood cells themselves – red and white blood cells and platelets. While the cellular components, like red blood cells containing hemoglobin, are crucial for transporting oxygen and white blood cells for the immune response, plasma acts as their carrier throughout the cardiovascular system.
Plasma is essential in maintaining homeostasis by helping to regulate body temperature, and by carrying nutrients, hormones, and waste products. The lymphatic system, which also plays a role in fluid transport and immune defense, moves lymph through similar muscular contractions, though not directly pumped by the heart.