What is the primary way the endocrine system regulates body activities?

• A. Uses enzymes
• B. Controls body activities through chemical messengers called hormones
• C. Does not influence growth
• D. Works through electrical impulses only

Answer: (B)

The main idea is that the endocrine system regulates body activities through chemical messengers called hormones. Glands release these hormones into the bloodstream, and they travel to distant target cells where they bind to receptors to trigger changes in metabolism, growth, reproduction, and homeostasis. Because these signals travel through blood, their effects are typically slower to start but longer-lasting than electrical signals, making them the primary means of sustained regulation. For example, insulin helps control blood sugar and thyroid hormones adjust metabolic rate. While enzymes play crucial roles inside cells, and the nervous system uses electrical impulses for rapid responses, the endocrine system’s core mechanism is hormone-based chemical signaling rather than enzymes or electrical signaling alone.