Chemical substances manufactured by glands of the endocrine system are called

• A. Hormones
• B. Enzymes
• C. Neurotransmitters
• D. Antibodies

Answer: (A)

Hormones are chemical messengers produced by endocrine glands and released into the bloodstream to travel to distant target organs, guiding processes like metabolism, growth, and reproduction. This long-range signaling is what sets the endocrine system apart from other chemical players: enzymes are cellular catalysts that speed up reactions inside cells; neurotransmitters are signals released by neurons to communicate across nearby synapses; antibodies are immune system proteins that fight off pathogens. Hormones coordinate body-wide functions, enabling the body to respond to changes and maintain balance. For example, insulin from the pancreas helps regulate blood sugar, while adrenaline from the adrenal glands prepares the body for quick action.