What substance does the circulatory system distribute throughout the body?

The circulatory system serves a crucial role in maintaining homeostasis and supporting various physiological functions by distributing essential substances throughout the body. Oxygen, hormones, and nutrients are vital components transported by the bloodstream.

Oxygen is carried from the lungs to the body's tissues, where it is used for cellular respiration and energy production. Nutrients, absorbed from the digestive system, are delivered to cells to support growth, repair, and metabolism. Hormones, which are chemical messengers produced by glands, travel through the blood to target organs and tissues, regulating numerous bodily functions such as metabolism, growth, and mood.

While other substances like waste products, carbon dioxide, and heat are also transported by the circulatory system, they do not represent the primary purpose of this system. Instead, their movement is often a result of the activities related to oxygen, hormones, and nutrients. Hence, the correct answer emphasizes the critical substances primarily distributed by the circulatory system, underscoring its essential role in sustaining life and promoting bodily functions.