Which of the following is NOT a function of the circulatory system?

The circulatory system plays a crucial role in maintaining various physiological functions in the body. One of its primary responsibilities is the transportation of nutrients and oxygen to cells, as well as the removal of waste products like carbon dioxide. Regulating body temperature is also a vital function of the circulatory system. This is achieved through adjustments in blood flow; for instance, when it's hot, blood vessels near the surface of the skin dilate, promoting heat loss.

However, producing hormones is not a function of the circulatory system itself. Hormones are primarily produced by endocrine glands and released into the bloodstream. While the circulatory system does transport hormones after they have been produced, it does not create them. This distinction makes the option about producing hormones the one that does not belong as a function of the circulatory system.