Blood is made up of several key components, each serving a specific function. The main components include red blood cells, which transport oxygen from the lungs to the body's tissues, and white blood cells, which are essential for the immune system and help fight infections. Additionally, platelets play a crucial role in blood clotting, preventing excessive bleeding. The liquid part of blood is called plasma, which makes up about 55% of its volume. Plasma contains water, electrolytes, proteins, hormones, and waste products. It serves as a medium for transporting nutrients, gases, and waste throughout the body, ensuring that all cells receive the necessary substances for proper function.