the circulatory system is... our heart, lungs, brain, and kidneys. our heart, lungs, and blood vessels. our…

Brief Explanations:

The circulatory system consists of the heart that pumps blood, blood vessels (arteries, veins, capillaries) that carry blood, and the blood itself which transports oxygen, nutrients, and waste - products. Lungs are part of the respiratory system, the brain is part of the nervous system, and kidneys are part of the urinary system.

Answer:

our heart, blood vessels, and blood.