Which system is primarily responsible for transporting hormones throughout the body?

• A. Circulatory System
• B. Nervous System
• C. Lymphatic System
• D. Respiratory System

Answer: (A)

Hormones travel through the bloodstream to reach distant target cells, so the circulatory system is the primary channel for distributing these chemical messengers. Endocrine glands release hormones into the blood, and as the blood flows through the body, hormones circulate until they encounter cells with specific receptors. When a hormone binds its receptor, it triggers a cellular response that coordinates processes across different tissues.

The nervous system uses electrical signals and neurotransmitters for rapid, localized communication, which is a different mode from circulating hormonal signals. The lymphatic system mainly handles immune functions and fluid drainage, while the respiratory system deals with gas exchange. None of these are the main highways for circulating hormones, making the circulatory system the best answer.