Which system is primarily responsible for regulating growth and metabolism through hormones?

The endocrine system is primarily responsible for regulating growth and metabolism through hormones. Hormones are chemical messengers that are secreted directly into the bloodstream by various glands within the endocrine system, such as the pituitary gland, thyroid gland, and adrenal glands. These hormones travel throughout the body to target organs and tissues, influencing various physiological processes, including growth, metabolism, and mood.

For instance, growth hormones, released by the pituitary gland, directly affect the development and growth of bones and tissues. Additionally, hormones like thyroxine from the thyroid gland play a crucial role in regulating the metabolic rate of the body, influencing how energy is used and stored.

The other systems mentioned have different primary functions. The respiratory system is involved in gas exchange and does not regulate growth or metabolism through hormones. The cardiovascular system focuses on the transportation of blood and nutrients throughout the body, while the digestive system is primarily concerned with breaking down food and nutrient absorption. Neither of these systems directly regulates growth and metabolism in the same hormonal manner as the endocrine system.