What are hormones primarily known for?

Hormones are primarily known for their role as signaling molecules produced in one part of the body to exert effects on another tissue or organ. This characteristic is fundamental to the endocrine system, where glands such as the pituitary, thyroid, and adrenal glands release hormones into the bloodstream, enabling them to reach specific target cells that have the appropriate receptors. The interaction between hormones and their target cells regulates numerous physiological processes including metabolism, growth, mood, and reproduction.

The other options do not accurately describe the primary function of hormones. For instance, while neurotransmitters play a critical role in the nervous system and facilitate communication between neurons, they are distinct from hormones, which operate through the bloodstream. Similarly, nutrients absorbed in the gut refer to the digestive process and are not related to hormonal signaling. Lastly, while some hormones can be synthesized artificially to mimic or replace natural hormones, this aspect does not capture the defining role of hormones in the body. Instead, their critical function stems primarily from their ability to influence various physiological processes across different tissues.