What is the role of hormones in the endocrine system?

Hormones play a crucial role in the endocrine system primarily by regulating metabolic processes. They are chemical messengers produced by various glands in the body, such as the pituitary, thyroid, and adrenal glands. Once released into the bloodstream, hormones travel to specific target tissues and organs, where they initiate a wide range of physiological effects.

For instance, hormones like insulin and glucagon are vital for regulating glucose levels in the blood, while thyroid hormones influence metabolic rates and energy expenditure. Additionally, hormones are involved in growth, development, stress responses, and the regulation of bodily functions such as digestion and reproduction. By maintaining homeostasis, hormones ensure that the body's systems work in harmony, adjusting metabolic activities according to the needs of the organism.

The other options reflect different biological functions not directly related to the primary action of hormones. For example, the transmission of nerve impulses is primarily the role of the nervous system rather than the endocrine system, while forming physical structures often pertains to the roles of proteins and other macromolecules rather than hormones specifically. Initiating reflex responses involves immediate reactions typically governed by neural pathways, showcasing a different mechanism of action compared to hormonal regulation.