Animal Form and Function

A. Endocrine Glands and Hormones Definition: Endocrine glands are ductless glands that secrete hormones directly into the bloodstream, while hormones are chemical messengers that regulate physiological processes in target cells or organs. Explanation: Endocrine glands are specialized organs that produce and release hormones without using ducts. Instead, hormones are secreted directly into the bloodstream where they travel to distant target cells. Hormones are chemical signaling molecules that bind to specific receptors on target cells, triggering specific responses. These responses can include changes in metabolism, growth, development, reproduction, and homeostasis. The endocrine system works slowly but has long-lasting effects compared to the nervous system. Think of it as: Think of endocrine glands as radio stations broadcasting signals (hormones) that travel through the air (bloodstream) to reach specific radios (target cells) tuned to that frequency (receptors).