Which are in the class of chemicals called flavanoids (what gives plants their color). Chlorophyll is the most well known pigment, providing all that green you see in leaves and foliage.
The respiratory and circulatory systems work with each other in this manner, the respiratory system will obtain oxygen then the circulatory system brings the oxygen to different parts of the body then it also takes carbon dioxide from different tissues of the body and bring carbon dioxide to lungs then the respiratory system takes carbon dioxide outside the body during exhalation