What system produces and secretes hormones?

The endocrine system is responsible for the production and secretion of hormones, which are chemical messengers that regulate various functions in the body. This system includes a network of glands, such as the pituitary, thyroid, adrenals, and pancreas, which secrete hormones directly into the bloodstream. These hormones influence growth, metabolism, reproductive processes, and mood among many other physiological functions.

In contrast to the endocrine system, the circulatory system primarily transports hormones and other substances throughout the body. The digestive system focuses on the breakdown of food and absorption of nutrients, while the respiratory system is concerned with gas exchange—taking in oxygen and expelling carbon dioxide. These systems serve distinct functions and do not primarily involve the production and secretion of hormones.