Associate Professor Mike Todorovic, AKA “Dr. Mike”, introduces the endocrine system, explaining how hormones act as chemical messengers released into the bloodstream by cells, tissues, and glands. He highlights three hormone categories—protein/peptide, steroid, and amino acid-derived—and their mechanisms of transport and action. Hormones bind to specific receptors located in cell membranes, cytoplasm, or nuclei, depending on their type. Comparing endocrine and nervous systems, Dr. Mike emphasizes their distinct speeds, durations, and communication methods. Covering hormone stimuli—neural, hormonal, and humoral—he details how these systems coordinate body functions. The video offers a comprehensive foundation for understanding hormone physiology and the endocrine system’s role.