The main function of blood in the body is to transport essential nutrients, gases, hormones, and waste products throughout the organism. Blood plays a critical role in maintaining homeostasis by regulating body temperature and pH levels. It consists of red blood cells, which carry oxygen from the lungs to body tissues, and white blood cells, which are involved in immune defense. Plasma, the liquid component, helps in nutrient transport and waste elimination. Additionally, blood aids in clotting processes to prevent excessive bleeding, making it vital for overall health and survival.