What are hormones?

• A. Nerve impulses in the brain
• B. Chemical messengers secreted by the endocrine glands
• C. Energy molecules used by muscles
• D. Waste products of metabolism

Answer: (B)

Hormones are chemical messengers secreted by the endocrine glands into the bloodstream, signaling various parts of the body to regulate functions such as metabolism, growth, and response to stress. They differ from nerve impulses because hormones travel through the blood and can have widespread, longer-lasting effects, while nerve impulses are electrical signals that act quickly and locally. The other options describe nerve impulses in the brain (not hormones), energy molecules used by muscles (ATP), and waste products of metabolism (like CO2 or urea). In sport and massage context, hormones influence healing, energy availability, and inflammation, which helps explain why hormonal balance matters during recovery and training. Examples include adrenaline from the adrenal glands during activity, insulin from the pancreas controlling blood sugar, and growth hormone from the pituitary promoting tissue repair.