The main function of the circulatory system in vertebrates is to transport nutrients, oxygen, hormones, and waste products throughout the body. This system comprises the heart, blood vessels, and blood, working cohesively to ensure that all body tissues receive adequate supplies for metabolic processes. The circulatory system plays a vital role in maintaining homeostasis, regulating temperature and pH levels while enabling the immune system to respond to infections. Efficient circulation is crucial for sustaining life and supporting overall health in vertebrate organisms.