The primary component of blood is plasma, which constitutes about 55% of its total volume. Plasma is a yellowish liquid that is essential for transporting various substances throughout the body, including nutrients, hormones, and waste products. It contains water, electrolytes, proteins, and other molecules that help maintain blood pressure and volume, as well as balance pH levels. The remaining components of blood include red blood cells, white blood cells, and platelets, which play vital roles in oxygen transport, immune response, and blood clotting, respectively. Together, these components work to ensure the body functions effectively.