The endocrine system regulates metabolism, hair growth, and reproduction through chemicals called

• A. Proteins
• B. Enzymes
• C. Nucleotides
• D. Hormones

Answer: (D)

Hormones are the chemical messengers of the endocrine system. Glands release them into the bloodstream, and they travel to specific target tissues to regulate metabolism, hair growth, and reproductive processes. This signaling system coordinates activities across the body, enabling metabolic rate changes, growth, and fertility to be adjusted as needed. Enzymes are catalysts that speed up reactions, nucleotides are the building blocks of DNA and RNA, and while some hormones are proteins, the term that best describes the signaling chemicals that orchestrate these broad physiological processes is hormones.